Can a once truly saved believer backslide too much and lose the gift of salvation? If so do they need to repent and ask for forgiveness through Christ again? Thoughts are welcome and scripture too!
The moment or stage of conversion may be described grammatically as occurring in the past: we were saved when we repented/received the baptism of the HS. From the moment of repentance onward begins the second stage of growth, discipleship (Acts 14:22) or sanctification (2Thes. 2:13), which is present progressive: it is the process of being saved now. This stage has two phases: instability and maturity. A new convert does not achieve immediate perfection by remaining filled with the HS (Phil. 3:12). Instead, the combination of temptations, ignorance of GW and the old selfish nature results in immature saints committing post-conversion sins, at which time they are carnal or acting like unbelievers (1Cor. 3:1).
As soon as new Christians realize they sinned, they should confess it (1John 1:9a) rather than compound it by trying to hide it or cover it up like Adam and Eve did (Gen. 3:7-8). Whenever a believer acknowledges to God his/her known sins of immoral attitudes and actions, God forgives all sins (1John 1:9b). This means he/she is pleasing rather than grieving God or once again is Spirit-filled (walking in the Spirit) and has a right relationship with Christ Jesus (Eph. 4:30, 5:10 & 18). This spiritual flip-flopping is the phase of instability, and although it is bad, failure to confess promptly is much worse, because it results in chain-sinning or back-sliding, which may be called prodigal if it continues very long (cf. Luke 15:11-32).
Unfortunately, some saints may not appreciate the process of spiritual growth or being transformed by the renewing of their minds (Rom. 12:2), perhaps because it involves admitting sins or having “guilt trips”. Guilt is like a warning light, and until we gain the wisdom to welcome God’s reproof, we will not feel the satisfaction of becoming a new and improved version of ourselves. Woe to the one who become so callous that no guilt is felt when wrong is done!