Here are scriptures telling us that those who fall away will lose their promise of salvation.

Hebrews 6:4-6

King James Version

4 For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost,

5 And have tasted the good word of God, and the powers of the world to come,

6 If they shall fall away, to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame.

Come Lord Jesus!