Another test as to Gregory of Nyssa's affiliation is who he considered the head of the church. If he only views Christ as the head of the church, then he falls more in the Reformed camp. If he also (or instead) views the bishop of Rome as the head of the church, then he falls more into the Romanist camp.
So, what does he say?
Paul's words show us the significance of Christ's name when saying that he is the power and wisdom of God. But he also called Christ peace, inaccessible light where God dwells, sanctification, redemption, the great high priest and Pasch, propitiation of souls, splendor of glory, stamp of [God's] substance and maker of the ages, spiritual food and drink, rock, water, foundation of faith, chief cornerstone, image of the great and invisible God, head of his body the Church, first-born among many brothers, mediator of God and of men, only-begotten Son crowned with glory, the principle of created beings which he, the beginning, said about himself (Col 1.18).
- Gregory of Nyssa, On Perfection
Notice that in this quotation, Christ is the head of the Church. This is the Biblical teaching, which we will see again and again in Gregory of Nyssa.
He who teaches Christ as the head of the Church [Eph 5.23] holds this observation as most important: the entire head has the same nature and substance as the body under subjection, and the individual members as a whole share a single unity effecting cooperation among the limbs in every activity. If anything is external to the body, it does not belong to the head. Therefore the head has the same nature as each member in order that they may conform to it. But we are the limbs which contribute to Christ's body. Should anyone who has become a limb of Christ do evil [1Cor 6.15] by taking up the sword of unbridled rage, this wicked passion has severed the limb from its head. Thus the remaining organs of evil become swords which severe limbs from the body's unity, and all the limbs are severed from the head as if the passions had made the cut.
- Gregory of Nyssa, On Perfection
Same reference to the Biblical metaphor.
In order that the entire body might have the same nature, each limb must be united to the head; if we consider the head to be pure by reason of its essence, the limbs must be made pure under such a head. If we understand the head as incorrupt, the limbs are necessarily incorrupt. As for the other notions with regard to the head, it follows that they are likewise perceived in the limbs: peace, purity, truth and so forth. This example and similar elements manifested in the limbs show an affinity with the head. The Apostle says that Christ is the head from whom the entire body is fit together and connected by every joint performing its task and which makes the body grow according to each member's capacity [Eph 4.16]. The term "head" also applies to animals as the principle for their bodies' actions; the eye and ear effects movement and action of their feet and limbs. Neither does the eye know its actions nor does the ear obtain guidance as it ought when things are brought to its attention: every impulse and action of our bodies must be moved in accord with the true head to wherever he who formed the eye or planted the ear directs it [Ps 93.9]. When the head looks above, the limbs ought to be united under the head's direction and have their impulse directed on high.
- Gregory of Nyssa, On Perfection
Same metaphor - notice as well that Gregory appeals explicitly to Scripture ("The Apostle says").
391.12: he is the head of his body the Church, the first fruit of our nature.
- Gregory of Nyssa, Commentary on Song of Solomon
The Apostles of the Savior were neither lamps, lights nor stars but messengers of light not illumining one region or area but brightening every place under heaven. The most important leaders were Peter, James and John who were designated as witnesses by Christ, running to the end of their lives and expending themselves by various forms of witness. For he whom the Lord designated as leader of the apostolic chorus obtained proper glory. By the cross he expressed the lordly image of the king (I mean the image of the cross of which he was not ashamed of suffering but took it as a great trophy. Neither we nor any other person, as Paul says, can say that Jesus Christ is our Lord. Thus Peter radiates with much holiness and reverence when he is suspended upside down on a cross in order not to equal himself with his Savior's glory which spread through his crucifixion to humanity in its entirety and whose embrace included the entire world. James was beheaded [cf. Acts 12.2] out of love for Christ his true head. As the Apostle says, Christ is the head of man and the entire church [cf. 1Cor 11.3, Eph 5.23]. Blessed John endured many, diverse conflicts and succeeded in various positions with regard to fostering the religion. He underwent an unsuccessful attempt at being drowned and was judged to be numbered among the martyrs' chorus. [John] was held in esteem not by his suffering but by his desire to undergo martyrdom, a type of death which became an immortal tribute who by his death had graced the churches. It is indeed fitting to recall those special men not only with regard to their outstanding piety but their noble character. Together they hold special rank among the other apostles, and their courage does not belong to human reasoning but is in accord with the judgment of divine truth.
- Gregory Nyssa, Two Homilies Concerning St. Stephen, Protomartyr, Second Sermon
Notice how Gregory views Peter as the "leader of the apostolic chorus" and considers him (along with James and John) to be of "special rank among the other apostles" but still reserves the title of "head of man and the entire church" for Christ.
Perhaps this inscription refers to the leader of the Church [ekklesia]. The true Ecclesiastes [ekklesiastes, Christ] gathers into one assembly those persons who often have been scattered and frequently deceived. Who could he be except the true king of Israel to whom Nathaniel said, "You are the son of God and the king of Israel" [Jn 1.49]? If these words pertain to the king of Israel, the Son of God, as the Gospel says, then he is called Ecclesiastes. We will not deviate from the inscription's meaning provided that we learn about him who firmly establishes the Church through the Gospel and to whom these words apply. "The words of Ecclesiastes, son of David" [1.1]: thus Matthew begins his gospel with the name David and calls him Lord.
- Gregory of Nyssa, Commentary on Ecclesiastes, the First Homily
The usual metaphor with the true head being Christ. The translator inserted the "Christ" in the first bracket above, but he is correct that Gregory is making that identification.
Those in the grave seek the voice of the resurrection; light is agreeable to persons in darkness, and a road is helpful for those who have strayed while a gate forms an entrance. And so Ecclesiastes speaks to those of us who belong in the Church. Let us who compose this Church now listen to his words. As a chorus looks to its leader, sailors to their pilot and soldiers to their general, so do those in the assembly of the church look to Ecclesiastes.
- Gregory of Nyssa, Commentary on Ecclesiastes, the Second Homily
It's interesting how Christ is not just the head, but the chorus-leader, the pilot, and the general of the church.
Now the great leader of the Church [Christ] indoctrinates us into loftier teachings. The preceding words have purified the soul and have banished the vanity of cupidity from mens' desire. Ecclesiastes leads our minds to the truth by pointing out the grief resulting from vanity and by lifting its burden from our shoulders. May the Church be learned in this teaching and realize that the beginning of a virtuous life consists in alienation from evil! The great David introduced a pure manner of living by means of the psalms; he did not begin [the psalter] with the perfection of blessedness. David did not first say that blessedness consists in doing all things well; rather, he compared a [blessed] person to a tree rooted by flowing waters, always green in good works and one who gathers at appropriate times the fruit of his own life [Ps 1.3].
- Gregory of Nyssa, Commentary on Ecclesiastes, the Fifth Homily
Again, it is the translator inserting "Christ," but he is correct in doing so, based on the context.
"There is a time to cast stones and a time to gather stones" [3.5]. The leader of the Church's ranks confirmed the strength of his hearers by his teaching that they may now cast stones at their adversaries and procure such stones.
- Gregory of Nyssa, Commentary on Ecclesiastes, the Seventh Homily
Again, the reference to Christ is a bit indirect. However, since - as we established above, the speaker in the book is viewed by Gregory as Christ, we can see he is referring to Christ as the "leader of the Church's ranks."
If we have gained knowledge about the enemy against whom we must fight and take up arms, we ought to learn about another part of the text, that is, when to make a treaty of peace. Who is the good commander? He enables me to win favor by peaceful means. Who is the leader of this army? The divinely inspired scriptures clearly depict the battle array of angels belonging to the heavenly army: "There was a multitude of the heavenly host praising God" [Lk 2.13]. Daniel saw a thousand thousands and thousand times ten thousand worshiping him [Dan 7.10]. The prophets testify to this, calling him the Lord of all the armies and Lord of hosts [Ps 23.10]. And to Joshua Nave, the powerful one in battle, he said, "I am the commander of the [M.749] army [of the Lord]" [Jos 5.14]. If we have understood the assistance we receive in battle and the leader of our allies, let us make a truce with him, fly to his powerful aide and become friends in order to secure his assistance. The great Apostle [Paul] teaches us how to gain intimacy with him and how to be united in friendship saying, "Having been justified by faith, we have peace with God" [Rom 5.1]. And, "We are ambassadors for Christ as though God besought you by us [saying], 'Be reconciled to God'" [2Cor 5.20]. As long as our shameful deeds made us sons of wrath [Eph 2.3] we were among those who opposed the right hand of the Most High. The Apostle says of him "He is our peace" [Eph 2.14], words which form the end and summation of all temporal reality. We who had once been God's adversaries have learned to accomplish all things in time in order to establish peace with ourselves and with him. If the virtues truly belong to the army of peace with which we must be associated, it would not be outside the sense of the text which refers the name of every virtue to the Lord of virtues.
- Gregory of Nyssa, Commentary on Ecclesiastes, the Eighth Homily
For if we have learnt what the good alliance is and who is the Commander of these allied troops, let us make a treaty with him, let us join his command, let us make friends with the one who has gained such power. The way to be attached to him is taught by the assembler of this league, the great Apostle, when he says Therefore, since we are justified by faith, let us have peace with God [Romans 5:1], and again, We are ambassadors for Christ, as though God were urging through us; we implore you on Christ's behalf, be reconciled with God [2 Corinthians 5:20]. As long as we were by nature children of wrath by doing what is wrong [Ephesians 2:3], we stood in the ranks of those who resist the right hand of the most high [Psalm 77:10/76:11]; but if we lay aside ungodliness and worldly desires, in holy, just and godly living, by making this peace we shall be joined to the true Peace. For so the Apostle says of him, He is himself our peace [Ephesians 2:14].
- Gregory of Nyssa, Homily 8 on Ecclesiastes (Ecclesiastes 3:8) (Hall/Moriarty Translation)
Christ is the good commander, the leader of the army, the "the Lord of all the armies and Lord of hosts."
By reason of their greatness, such men are soldiers of Christ armed with the Holy Spirit, champions of faith and towers of the divine city. They resist every infliction of torture, fear, threats and foolish, shameful ridicule; they appear to offer their bodies to such outrages, but these are merely shadows. Such persons who are in the flesh defeat the flesh and have contempt for death; they disdain all fear of tyrants and appear more noble. How lovely are those trained in such bodily victories! How wonderful is their training when applied to combat against the devil! They are not armed with swords, shields, helmets nor leg protection; rather, they are armed with the full armor of God which the divine Apostle [Paul], the leader of the Church, illustrates: a shield, breastplate, helmet and sword (Eph 6.11+). These weapons are used against the enemy's forces, but divine grace supports them against the devil's troop which has the power to inflict death. This troop takes its stand in the tribunal, the place of decisive contest, where blood is shed; here [the devil's band] makes it threats and fights against those who patiently resist it.
- Gregory of Nyssa, Two Homilies regarding the Forty Martyrs, Second Homily (part 2)
Interestingly, here Gregory refers to Paul, not Peter, as the leader of the Church. It's the only time I could find where Gregory refers to anyone other than Christ in this way. Interestingly, I cannot find him referring to Paul as even one of the foremost apostles, but he gets the title "the leader of the Church." Not something one would expect from a Romanist author.