Read Romans 3:4 Using Other Translations
God forbid: yea, let God be true, but every man a liar; as it is written, That thou mightest be justified in thy sayings, and mightest overcome when thou art judged.
By no means! Let God be true though every one were a liar, as it is written, "That you may be justified in your words, and prevail when you are judged."
Of course not! Even if everyone else is a liar, God is true. As the Scriptures say about him, “You will be proved right in what you say, and you will win your case in court.”