Hebrews 6:4

4 For it is impossible to restore again to repentance those who have once been enlightened, who have tasted the heavenly gift, and have become partakers of the Holy Spirit,

Hebrews 6:4 In-Context

2 with instruction about ablutions, the laying on of hands, the resurrection of the dead, and eternal judgment.
3 And this we will do if God permits.
4 For it is impossible to restore again to repentance those who have once been enlightened, who have tasted the heavenly gift, and have become partakers of the Holy Spirit,
5 and have tasted the goodness of the word of God and the powers of the age to come,
6 if they then commit apostasy, since they crucify the Son of God on their own account and hold him up to contempt.
Revised Standard Version of the Bible, copyright 1952 [2nd edition, 1971] by the Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.