Radhanath Swami: The nature of everyone is to believe in God. But because of conditioning in this material world people want to be the enjoyer rather than the servant, and when that enjoying spirit becomes like a fever, they consider God as an impediment; they consider God’s laws as an impediment. Therefore their minds reject the conception of God, just to justify their own independent behavior. So it is due to long conditioning of exploitation in this material world that people lose faith in God. But through proper association that faith can be reawakened, because it is the nature of the soul to have faith. It is just covered by the cloud of conditioning, but through proper association that cloud can be dissipated.
Now, regarding convincing others, the best way to convince others is not simply through academic information, but through our own conviction and faith. Someone may speak tens and thousands of shlokas to prove the existence of God, and the listener may think it is all just fanciful, superstitious ideologies. But one who really has faith and conviction can just say a few words and convince the listener.
When Srila Prabhupad was in New York in 1965, do you know that most of the people who were sitting in his classes could hardly understand his Indian accent? They hardly understood what he was saying. They could catch a few words here and there. But he totally convinced them to surrender their lives to God, because he was himself convinced. Whatever few words that they could understand from what he was saying penetrated their hearts and transformed their lives. Why? It was spoken with such conviction, with such realization, and with such faith. So if you want to convince others, the best process is to be convinced.