How do we know that true believers will not fall away?

The assurance of a believer's perseverance is rooted in the understanding that they are kept by the power of God, as highlighted in 1 John 2:19. Those who genuinely belong to Christ may experience temporary struggles or doubts, but they are ultimately sustained through God's grace. Philippians 1:6 reinforces this belief, stating that He who began a good work in us will carry it on to completion. Consequently, genuine believers, being sealed by the Holy Spirit, are given an unction to recognize and know the truth, thus ensuring they do not permanently fall away but will return to a sound understanding of the Gospel.