I have a friend that seems to have trouble accepting Paul's writings and spends all his time in the O.T. What can I possibly tell him to help him in this area. I have talked to him and prayed, please help me to help him.
I'm not too sure what you can tell your friend as I doubt his real hangup is Paul but rather Christ himself. After all, there is nothing inherently wrong with the Old Testament writings, but there's a good chance that his trouble with Paul's writings is indicative of his own trouble with a grace that is given to the unworthy and elusive to the self-righteous.
Remember that when Jesus hit the scene he didn't have Paul's writings either, which are the truth of what he was about to bring to pass. For he dealt with those who only had the writings of old covenant. HE was the life that was among them. His ears were the very ears of the Spirit that heard beyond the shallow professions of something they did not have. His mouth was the very mouth of God that pierced through with an unknown-to-the-flesh authority that caused many to realize that he spoke as God himself. His heart was the heart of God that loved beyond the rigid boundaries of performance.
When he heard their self-righteous claims he challenged them by the very law they thought was their validation declaring that it was to be fulfilled in HIM. When there was rejection of the down-trodden, the despised, the foreigner, the helpless, the sinner, etc. he asked how they had ever overlooked the very heart of God as witnessed by those OT writers. To the rejected, he revealed the salvation of God that had been hidden within the writings that had rejected them.
How can you help your friend? Listen to his heart and speak to what you hear. After all, the life in you is the life of God in Christ!!