The Bible talks about motes (specs of dust) and planks.
Both need to be removed and the removal process is the same.
Sins are of different sizes, but pride in being a lesser sinner is ridiculous.
But today I hear of some sins being 'unpardonable'.
Once properly with God, to then walking away is 'insane', and one then cannot come back, apparently.
Or to allow oneself to become a compulsive nurser of your own grudges is also a problem, or so I'm told.
And also wilful or careless negligence whilst claiming to be of God/Christ is also pretty bad.
Also one cannot serve 2 masters, so if one finds oneself in this situation (too often in 2-minds about important matters -- see 'double minded' in 'James') and fails to take remedial action, then this is pretty un-Christian too !!
Also mentioned was the sin of being affectatious with silly pretentions / pretentiousness.
Also mentioned was sinning wilfully and then staying in that sin.
Also mentioned was rejecting people for reasons that are uncharitable / un-Christian.
Also mentioned was congregation leaders who are corrupted in faith and the dangers of following such 'gurus', instead of God through Christ.
So, be very careful about over-trusting a 'guru' ('local flock leader') without verifying all of your understandings through study guided by the Holy Spirit supported through sincere and contrite prayer.
Do not rest on your own understanding, but don't rest on the understandings of others either, unless that other is Jesus !!