Why would your pattern for forgiving another come from Matthew, Mark, Luke and John? It's not written to anyone in the dispensation of the grace of God. It is written TO the lost sheep of the house of Israel, to whom Jesus was sent while on earth (Matthew 15:24 KJV, Romans 15:8 KJV).
Our pattern for forgiving one another is that we should because God for Christ's sake hath forgiven us.
Ephesians 4:32 And be ye kind one to another, tenderhearted, forgiving one another, even as God for Christ's sake hath forgiven you.
And as to God not forgiving us our trespasses, just how many of your trespasses do you believe are not forgiven already (Colossians 2:13 KJV)?
I'm surprised at the OP coming from you, Psalmist. I thought you knew better; especially considering you are a chaplain. You really need to get into Romans through Philemon and consider what Paul says (2 Timothy 1:13 KJV, 2 Timothy 2:7-8 KJV).
The four Gospels bring the message of hope to a lost and dying world, to anyone who will listen. They exposed to the truth John 14:6, we always hope it will lead to Romans 10:9-10, 13, Saved!
John 10:16
"And other sheep I have which are not of this fold; them also I must bring, and they will hear My voice; and there will be one flock and one shepherd."
Acts 28:28-31
28 "Therefore let it be known to you that the salvation of God has been sent to the Gentiles, and they will hear it!" 29 And when he had said these words, the Jews departed and had a great dispute among themselves. 30 Then Paul dwelt two whole years in his own rented house, and received all who came to him, 31 preaching the kingdom of God and teaching the things which concern the Lord Jesus Christ with all confidence, no one forbidding him.
John 10:16
"And other sheep I have which are not of this fold; them also I must bring, and they will hear My voice; and there will be one flock and one shepherd."
Acts 28:28-31
28 "Therefore let it be known to you that the salvation of God has been sent to the Gentiles, and they will hear it!" 29 And when he had said these words, the Jews departed and had a great dispute among themselves. 30 Then Paul dwelt two whole years in his own rented house, and received all who came to him, 31 preaching the kingdom of God and teaching the things which concern the Lord Jesus Christ with all confidence, no one forbidding him.