Hopefully making theology simpler to understand! (2 Corinthians 1:12)

If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.
1 John 1:9, ESV

Both as Christians and not, we continue to sin. It is in our nature until Christ returns.
But, by Christ’s sacrifice and resurrection, all our sins – past, present, and future – are forgiven if we trust Him, confess, and repent.