The world disputes and denies the existence of God because it is looking for a physical appearance of a god. God is spirit and therefore we cannot see Him. No eye has seen Him, neither ear has heard Him, neither physical senses have sensed Him, because a God is beyond our physical senses.
God revealed Himself in Jesus Christ, who came as a man. The world did not recognize Him. The religious people rejected Him, they crucified Him because they did not accept the revelation that God gave of Himself. They were looking for something that they themselves did not know. Jesus Christ was resurrected and He ascended to heaven and once more He reveals Himself to those who obey His words, His gospel. Jesus said:”The one who loves Me is the one who has my commands and who keeps them.” If we obey the gospel of Jesus Christ, repent and be baptized and live according to His commands, then Him and the Father will come and live with us and He will reveal Himself to us.
The reason why the world does not know God is because they reject God, they reject Jesus Christ. They are looking for their own God, their own image of a God. If we seek the truth we will find it. Jesus Christ is the way and the truth and the life and He reveals Himself to those who seek the truth. Those who are pure in heart will see God. If we seek Him we will find Him. If we draw closer to Jesus then He will draw closer to us, He will reveal Himself to us and we will know Him for real. Therefor the world and most believers do not know, Jesus they are looking for an image of their own liking, but they reject the revelation of God.
Have you met the living Jesus? Do you believe and do you obey Him? Has He revealed Himself to you? Do you know His voice? Do you observe Him in your spirit, and do you serve Him? Have you found the Living God, Jesus Christ?
May Jesus bless you.