One basic Christian belief has for a long time been the Trinity, in which you do not believe.
God in three persons as opposed to God is three persons.
Hence Jews call it a triune not a trinity.
I believe in God, I believe In Jesus and I believe in the Holy Spirit. Like Christ, I believe there is only one God.
The Father is God, Jesus is the Son and then the Holy Spirit three persons.
I don't believe in a manmade idea that all three make one God but that God the Father is in all three.
I presume you're referring to St Paul's idea of "By faith, Abraham was counted righteous" - the only part of the Law that St Paul didn't dispense with. I suggest he only clutched at the reference to Abraham because the Roman authorities would only give any credence to a foreign religion if it had some kind of ancient pedigree, and he knew his new religion would never make headway without providing some.
Paul did not dispense with the LAW. He simply told people that obeying the law was not enough and that the only way to have your sins forgiven was through Christ. It is understanding that Christ did not do away with the Law or teachings of the Prophets. We uphold them but they do not bring forgiveness or Gods righteousness as the way through Christ and forgiveness of sins removed.