Prayer is the opening of the heart so we can receive all these good things that God has for us every day. It's like sitting down at a table that God has prepared for us. He says, 'I have everything you need today - all the grace, all the wisdom, all the provision that you need - but sit down at the table and eat. Don't be so rushed and so busy and try to live without My supply.'
By not forgiving, by not letting wrongs go, we aren't getting back at anyone. We are merely punishing ourselves by barricading our own hearts.
The devil is not terribly frightened of our human efforts and credentials. But he knows his kingdom will be damaged when we begin to lift up our hearts to God.
People who have a seeking heart still make mistakes. But their reaction to rebuke and correction shows the condition of that heart. It determines what God is able to do with them in the future.