Ok, christ does fulfill the law but also brings the new covenant "A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another. By this shall all men know that ye are my disciples, if ye have love one to another." The fundamental unarticulated presupposition that underpins what you are saying is that modern liberalism provides an ethical framework and overarching lens through which we see all other moralities as subordinate. When you say "most people want to do good" is that 'good' in the sense of what fits into a modern liberal framework? a kind of mediocre standardised ethic that allows markets to function smoothly but doesn't really try and justify itself, because different religions have very different ideas of what is moral.