In people saying God knows everything and claiming that Jesus would be God, adversaries of God receive an easy gainsaying danger because they can see how Jesus not at all knew everything, or in case he knows everything than it is clear that Jesus would not have told the truth on more than one occasion and as such would be a liar. The God of Jesus has man given the own possibility to choose what to believe and what to do, therefore it is up to man to make the right choice and to believe in the Only One true God or in the god man has created for himself or to please himself.
Though many things may be very difficult to proof that does not mean that they would not exist. Also feelings and experiences are difficult to proof, though the results of a God-Being in our life is something what many feel. One thing is for sure: "If God does not exist, then everything is permitted". In the transcendent reality we can not see nor fully understand God but somehow looking around us and listening to our inner feeling each person should be able to come to recognise the Supreme Power and to understand that reality is shaped by a Power beyond us.