I find the best way to prove God to people is first prove to them that they were created with the 4 Step Proof and then show them Jesus is God.
Once they realize that none can compare to Jesus, they know Jesus is God and need salvation, if they can appreciate they are sinners needing redemption.
It is that easy. The only difficulty is time. If they don't want to give you the time, you can't convice them. If you are sitting across from someone 5 hours a day trying to convince them, how could they not finally give into the truth. They still may not, because ulimately it is their choice.