Considering the evangelist's calling to make ordinary people into saints: If someone believes in God and believes also in Jesus then they are two steps towards being persuaded to follow the teachings of Jesus persistently. If they don't even believe in God then trying to persuade them to do so is a challenge. Personally I have tried proving God exists by saying the chances of the Earth not having been created is unimaginably small, given that even humans could expect to aquire the ability to terraform a planet within tens of thousands of years and the chance of nobody else in the Universe being able to do that within the age of the Universe is unthinkable. But that only 'proves' Earth was terraformed to support life. It doesn't prove the God who did it made the Universe itself and made Jesus beforehand as first of His works.
