Salvation is something that permanently impacts our lives. When we believe that Christ died for our sins, was buried, and rose again on the third day according to the Scripture, we are saved. This is not something that we can lose, destroy, or otherwise reject. Even when we turn our back on God, He is faithful and will not turn His on us.
For it is not inherently possible, the ones once enlightened, both tasting of the heavenly gift and having become a partner of the Holy Spirit, and both having tasted a good utterance from God and inherent ability of the coming age and after falling alongside, to be renewed unto repentance, again crucifying and publicly shaming for Himself the Son of God – Hebrews 6:4-6