Question: Sir, Is it impossible for a Christian to repent if he or she commits apostasy?

Answer: The passage pertinent to your question is Hebrews 6:4-6–“For it is impossible to restore again to repentance those who have once been enlightened, and have tasted the heavenly gift, and have shared in the Holy Spirit, and have tasted the goodness of the word of God and the powers of the age to come, and then have fallen away, since on their own they are crucifying again the Son of God and are holding him up to contempt.” This scripture proves that it is possible for a Christian to fall away.   It does not teach that God will not allow a fallen Christian to repent.  Nor does it teach that a fallen Christian who desires to repent is incapable of doing so.  Rather, it gives a realistic appraisal of the likelihood of being able to reach someone who, after experiencing the glorious blessings of being in Christ, has rejected them.  Heaven has no greater incentives to offer!  Any who have fallen away could repent.  The question is, would they?