The heavens declare the glory of God; and the firmament shows His handiwork. Psalm 19:1, NKJVIn his letter to the Romans, the apostle Paul held the entire human race accountable for basic knowledge of God, which he declared "is plain to them, because God has made it plain to them. For since the creation of the world God's invisible qualities - his eternal power and divine nature - have been clearly seen, being understood from what has been made, so that men are without excuse" (Rom. 1:19-20, NIV).
Even tribal people isolated in jungle huts or desert tents have the fundamental testimony of creation. Through the faithfulness of the sun to rise and set, through the orderly pattern of the stars in the sky, through the miracle of reproduction and birth, and through a myriad of other silent witnesses, the human race has been confronted with the truth. And unless we deliberately repress what we instinctively recognize in the silent witness, we would acknowledge and come to the truth.
The real reason many people reject Jesus, at least in the Western Hemisphere, is repression and rejection of what they instinctively know to be the truth - that there is one, true, living God who created us all and has revealed Himself through the Person of Jesus Christ.