You would be very hard-pressed to find a respectable historian who believes that Jesus did not exist. There is arguably more good evidence that Jesus existed than did Alexander the Great. Whether or not he did all the things he is reported to have done is perhaps another matter. The issue of Jesus’ existence, however, is so well established historically, that it is almost never seriously disputed.
We must look to God for His grace and His power to perfect godly qualities in our lives.