The "abiding" part is where you are missing the Faith.
See, here is how you are understanding it..
"God saves me when i believe, and then i try to stay saved by doing stuff, "abiding", "good works", enduring to the end".
You are not grasping that all those are works., and what has happened is that you have stopped trusting in God to save you through Christ, "Grace" and have instead decided that you can save yourself by effort.
The issue is, Salvation does not require your effort., it only requires that you are born again.
Just more of man's opinion and human reasoning with no scripture.
The only way faith will produce a divine result is by the effort obedience requires.
Repent is how we receive the forgiveness of sins.
Forgiving others is an effort that allows God to forgive us.
There is therefore now no condemnation to those who are in Christ Jesus, who do not walk according to the flesh, but according to the Spirit. Romans 8:1
Our choice is to put forth the effort to walk according to the Spirit, rather than walking according to the flesh, so that we can live free from condemnation.
JLB