Lee Shelton IV has an interesting article on the command to be fruitful and multiply (link). Shelton seems to take the view that we should - in essence - spiritualize the command to be fruitful and multiply in the New Testament era. I respectfully disagree.
The relevant Scripture is:
Genesis 1:28 And God blessed them, and God said unto them, Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth.
This was a creation ordinance. It is not part of the Mosaic law, and it was not fulfilled by Christ. We can see that it was not fulfilled by Christ, for example, from the fact that there is no record of (and no reason at all to suppose) Christ marrying. But more importantly, we can see it from the fact that it predates the Mosaic administration of the covenant of grace, and even predates the fall of man.
While we certainly should make disciples of all nations, spiritually being fruitful and multiplying and replenishing the earth and subduing it to the Gospel, that is not the primary sense of the text, but simply an application we can make via analogy. The primary sense is the literal sense.
We can determine this exegetically. Almost the same command shows up again after flood:
Genesis 9:1 And God blessed Noah and his sons, and said unto them, Be fruitful, and multiply, and replenish the earth.
From the two contexts in which see that command, we see that it is a command for literal procreation: a command to have children at more than a replacement rate.
If anyone will argue further, we can see that a similar commands were made with respect to animals:
21And God created great whales, and every living creature that moveth, which the waters brought forth abundantly, after their kind, and every winged fowl after his kind: and God saw that it was good. 22And God blessed them, saying, Be fruitful, and multiply, and fill the waters in the seas, and let fowl multiply in the earth.
So also, to Noah God said:
Genesis 8:17 Bring forth with thee every living thing that is with thee, of all flesh, both of fowl, and of cattle, and of every creeping thing that creepeth upon the earth; that they may breed abundantly in the earth, and be fruitful, and multiply upon the earth.
And it is arguable whether God addressed the following command to the animals or Noah and his family, though the former seems more likely in context:
Genesis 9:7 And you, be ye fruitful, and multiply; bring forth abundantly in the earth, and multiply therein.
Note as well as that this is not simply a command, but a blessing. Viewed as such, we should not consider it as an absolute command. It was not required, as Shelton seems to imagine, that men were required to have absolutely as many children as possible, without considering anything else. Indeed, if that were the case, one would expect to see Jesus with a large family and many children.
Even the papists recognize that the command was not absolute. Thus, they limit the command to married folks, and then further to married folks who engage in copulation. Ultimately, it is all for naught.
The command simply is not universal and unexceptional. There are men who are eunuchs - by nature, by their own will, or by imposition of others. There are women as well who are barren. Indeed, it is God who opens the womb.
Thus it is written:
Psalm 128:3 Thy wife shall be as a fruitful vine by the sides of thine house: thy children like olive plants round about thy table.
Genesis 29:31 And when the LORD saw that Leah was hated, he opened her womb: but Rachel was barren.
Psalm 127:3 Lo, children are an heritage of the LORD: and the fruit of the womb is his reward.
This is not simply for the Old Testament time. No, likewise in the New Testament it is the norm for men to have natural children:
Titus 1:6 If any be blameless, the husband of one wife, having faithful children not accused of riot or unruly.
By natural children, I do not of course exclude adopted children, but simply differentiate between children physically and children spiritually.
There can be overlap, certainly. As Paul explains:
1 Corinthians 7:14 For the unbelieving husband is sanctified by the wife, and the unbelieving wife is sanctified by the husband: else were your children unclean; but now are they holy.
You see, the mission field can begin in the bassinet or crib. We are to come to the Lord, and we are to bring our children, following the example here:
13And they brought young children to him, that he should touch them: and his disciples rebuked those that brought them. 14But when Jesus saw it, he was much displeased, and said unto them, Suffer the little children to come unto me, and forbid them not: for of such is the kingdom of God.
So, I must disagree with Shelton's apparent conclusion (which he qualifies by "one might argue that") "the Old Testament command was merely a prelude to the Great Commission." It is a prelude - for the promise to Abram:
Genesis 17:6 And I will make thee exceeding fruitful, and I will make nations of thee, and kings shall come out of thee.
is spiritually fulfilled in us, as Paul tells us. Nevertheless, it is a creation ordinance. It has not passed away, though it will (apparently) in heaven. For there:
Matthew 22:30 For in the resurrection they neither marry, nor are given in marriage, but are as the angels of God in heaven.
May God's kingdom come!