People should know that false teachers will teach anything they believe, and not from the Bible. People also should look at the preachers their behaviour and see if they have the Holy Spirit in them, following, living according and teaching the words of the Holy Bible. Often their way of talking, using a language which is not according the way Jesus would talk shall dismantle them and should be a sign for you that they are not the right one to follow.
In mankind's history there can be found natural theology which is generally characterized as the attempt to establish religious truths by rational argument and without reliance upon alleged revelations. Newt to it we may find lots of name-Christians trying to proof God exist but for them Jesus being God, others can see that their idea of God being Eternal, Immaterial, Transcending space, The Creator and Designer of the universe, Omnipotent, Omniscient, The unique greatest possible Being, does not fit at all their Jesus-god. Many people putting 2 and 2 together decide then wrongly because those qualities not fitting Jesus, he is not being able to be God but then there than also not being a Supreme God.