I believe what I mentioned (believe in Jesus as his lord and savior) covers “atone for our sins”.
I’m not a pastor. So my words aren’t exactly “Ready for Sunday morning service” and my ability to quote scripture is woefully inadequate but it in the right direction.
As a layman I’ll put my “preaching” up to Samantha Bee’s pastor any day.
The critical issue is who is atoning for your sin: Jesus or you? I am trusting in Jesus to atone for my sins.
As a start I would encourage you to read the epistle to the Romans and understand the essential difference between faith and works and the proper function of works.
I know it is a difficult place to start and there is much I do not yet fully understand, but there is much that can be understood.