What is temporary faith?- Menno John Bosma, Exposition of Reformed Doctrine, pp. 196-97
It is a receiving of the word straightway with joy, often caused by artificial methods.
What is lacking in a person having temporary faith?
A regenerated heart and therefore godly sorrow for sin and absolute surrender to Christ.
The name temporary faith is derived from the parable of the Sower, wherein Jesus describes those who are like seed sown on rocky places, and declares they endure only for a time.
Matt. 13:20, 21: "And he that was sown upon the rocky places, this is he that heareth the word, and straightway with joy receiveth it; yet hath he not root in himself, but endureth for a while; and when tribulation or persecution ariseth because of the word, straightway he stumbleth."
This temporary faith may last a shorter or longer time, sometimes till death, sometimes its true nature will be sooner discovered, as Jesus says in days of persecution or tribulation, or it may and often does fail when the stimulus and excitement which has produced it is taken away. An example of temporary faith is found in the history of Demas, who was once a companion of Paul, Col. 4:14, later he forsook him, "having loved this present world." II Tim. 4:10.
In what does temporary faith differ from saving faith?
Jesus says they who endure for a while have no root in themselves.
In this their principal difference from those having saving faith is found. True believers have the true root of faith in the depths of their hearts, implanted within them when they were born again by the Holy Spirit. Temporary believers lack this true principle of faith, for they were never regenerated; their faith does not therefore proceed from the depth of their hearts and control the whole soul, but is much more a temporary affection of the emotions; it is not accompanied by sincere sorrow for sin as saving faith is, but straightway, when the emotions have been stirred, it receives the promise and assurances of the Bible with joy, it is sure of salvation without having forsaken the old sinful life, it applies and appropriates something to itself that does not belong to it. A peculiarity of temporary faith is that it is intent wholly on its own enjoyment and salvation, but cares little or nothing for the honor of God, it is selfish.
Temporary faith differs from saving faith therefore in character as well as in duration.
When is temporary faith most likely to be found?
In stirring times, as in periods of war, famine and pests, and especially during some man-made revivals of religion when people are agitated and excited but not deeply convicted, not changed in heart.
Notice that for Bosma the difference is not simply one of duration (i.e. that temporary faith doesn't last) but one of kind (arising from an unregenerate heart).