Belief spreads through human teaching, not divine communication
Summary
An aphorism states that "It's always a man who says: 'God said ...'".
In fact, God, in his deistic conception, should reveal himself to man in an unconditional, intelligible and universal way.
In reality, however, this revelation is only made through human media, in a favourable family environment, through teaching and from one generation to the next.
A real presence of God should transcend these necessary conditions, and spread beyond cultural and/or geographical constraints (assuming that the entire population is not capable of receiving the message). Revelations should touch every corner of the globe and every community. And the problem of the uniqueness of the divine message (depending on religion, or obedience) should itself be overcome. In other words: God should naturally make everyone agree on the question of his presence.
A spiritual event such as evangelization or mass conversion could provide the beginnings of proof that this message is transcendent, but no such trend has been proven in human history. Belief is always spread by coercion or indoctrination. Is this really a divine path, or rather a merely human process?