How can we please the Heavenly Father? Of course, obedience, striving to live right, in love for Him, in good relations with all people. Errors must be corrected, not forgotten ...

So, holiness is the result of working on oneself under the guidance of the Lord.
How to believe that you are free from sin? I think it means deciding to live like this, choosing to do the right thing. Then trusting in the Lord will not be useless.

God has already completed his work - he has given you a new heart, but you need to take care of it, work with it like a little child, teach your mind and body to obey God.
I must die to sin myself, this is my cross. Live for others, this is freedom ...