Temporary belief is a real but unrooted reception of the gospel that springs up for a time and is then choked or scorched away, never becoming rooted life in Christ.
In the parable of the sower, seed on rocky ground springs up quickly and with joy, yet withers for lack of root; seed among thorns is choked by the cares and riches of this life. This belief is genuine as an experience — it is not mere pretence — but it never takes root as the person’s enduring life.
It should not be described as regeneration later lost or as salvation forfeited. It is the difference between a response that endures and one that does not: saving faith holds fast; temporary belief lets go.
See in Scripture: Luke 8:13; Matthew 13:20–22; John 2:23–25; Hebrews 3:12–14