On the point of the questioner’s real question, I started to look at how often we Christians are sidestepping this question, “Why Jesus” and replacing it with “Why faith”. If you look again at what I said the witness rests upon, it is strongly positioned on the basis of our own lives and character. This is why the ‘works’ part of our lives is so important. And the reason hypocrisy is so deadly. Whether we are given audience in the inquirer’s mind or not, and how efficiently God can substantiate the claims is influenced by how purely and sincerely our lives illlustrate what we believe.
We don’t have to be perfect, but we do have to be truthful. God can use all means to relay His message, but it is more useful to have faithful messenger than one who is not.
This is not a theological basis for why we should be truthful and mature in Christ- it is more about the bearing of such things on being able to relay message of the gospel, which is telling the world about Jesus Christ and what He has done, and what is given in His name. The gospel is not about us, or our church, rather these things are about the effect of Jesus Christ, and His evidence in the earth.
Since this is just a sidethought I am not going any further with it right now. It does lead me to the admonition of James on the nature of religion.