Many make the claim that they are New Testament only Christians. I have heard at least one story about a preacher who tore the Old testament from his Bible and threw it in the trash as part of his Sunday morning preaching.
The New Testament without the Old Testament is an incomplete Bible. Paul called the Old Testament scripture.
Romans 1:2 “Which he promised before through his prophets in the holy Scriptures”.
The writers of the New Testament were very familiar with the Old Testament. They quoted frequently from the Old Testament. When a quote from the Old Testament is found, one is expected to know the context of that quote in order to understand the passage in the New Testament.
Additionally, the statutes that explain the commandments found in Romans 13 are not found in the New Testament. One must search the Old Testament to learn what the commands mean. For example, adultery is not just about breaking wedlock. Use the scriptural definitions and not the dictionary for better understanding.
Be a whole Bible Christian.