Question:

Is repentance a gift or something we muster up?

Answer:

Repentance is a gift. First of all, repentance unto salvation is the counterpart of faith. They never are apart. Saving faith is faith in Jesus Christ as the Savior from sin! (Luke 13:3, 5) Saving faith is a gift from God (Ephesians 2:8-9); otherwise we could boast in the "good work" of faith. Verse 10 goes on to say that we're "created in Christ Jesus unto good works ..." God alone is the Creator.

In addition, the writer of Hebrews says of those who have experienced a work of the Spirit and then fall away, "It is impossible ... to renew them again unto repentance." Why impossible? Because God gives repentance. This is a passage dealing with the sin unto death—against the Holy Spirit—which Jesus refers to in Matthew 12:31-32. And lest one should infer from the Hebrews passage that it is possible to be saved and then eternally lost, see verses 7-9 in which the writer expresses his confidence that his readers have not apostasized, but are saved.

Those verses are a condensed version of our Lord's parable of the sower in Matthew 13; only seed falling in good soil can bear fruit. And, as to true apostates, John tells us in 1 John 2:18-19 that "They" (antichrists such as Judas Iscariot) went out from the apostolic fellowship because "they were not of us."

So repentance is a gift of God's grace. Jesus said in John 6:44, "No one can [is able to] come to me except the Father draw him, and I will raise him up at the last day" (meaning that those whom the Father draws to Christ will attain to the resurrection of the just).

I hope that completes the picture from the Scriptures. Please feel free to return if this isn't sufficiently clear.