The issue is that some are falsely told that you only have to repent once, and all sins past, present, and future are forgiven.
This is false, future sins are not forgiven unless you repent and ask forgiveness when they happen.
When the scripture says all sins will be forgiven, it is talking about the kinds of sins that will be forgiven, not when they happen.
Here James is talking to fellow brothers and sisters in Christ that are in a saved position.
James 1:14-15
" But each one is tempted when he is drawn away by his own desires and enticed. Then, when desire has conceived, it gives birth to sin; and sin, when it is full grown, brings forth death.
And then Timothy here:
1 Timothy 5:22
" Do not lay hands on anyone hastily, nor share in other people's sins; keep yourself pure. "
How can one become not pure if they share in other people's sins if that sin will already be forgiven. It won't be forgiven unless they repent and ask forgiveness of it.
Then you have others like Romans 8:13 where Paul is speaking to fellow brothers and sisters in Christ, telling them not to walk in sin that will lead to death, but walk in the spirit that will bring life.