Humans at all times and in every place believe in the existence of God.
Prehistoric structures (Stonehenge in England, Hagar Qim and the Hypogeum in Malta, etc.) all testify to the fact that man is a "religious animal," distinct and radically different from the beasts and all living creatures upon the face of the earth. The earliest civilisations (Sumerians, Egyptians, Incas, etc.) all without exception has a strong sense of religion; these people all attempted to Re-ligio, to be bound to their Maker and Superior.
Their earliest records and structures all point to the fact that religion is not an opium for the people, as Marx mistakenly believed. It is rather his desperate and unsuccessful attempt to make amends with God.
Admittedly, he is the Unknown God, as Paul took the hint from one of the numerous Athenian altars, who is worshipped in ignorance, in superstition and idolatrously. But man, inevitably, lives and moves and exists in Him. He is the offspring of God and therefore man is incurably religious.
This pervasive idea of God has been explained away by some modern anthopologists. In our Scientific era, when we know what causes lightning and rain and earthquakes and tornadoes, we no longer have room for God. These events that used to terrify our forefathers are easily explained now. So the idea of God is outdated and needless. Not so! For the most learned men are still religious. They are still influenced by their belief, however warped and inconsistent, in a Supreme Being. Logic and reason are both within man's constitution, but these have never defaced the notion that there is a God. Man still desires to worship and bow down, even though it be (quite illogically) before stocks and stones. People may arrogantly live as if there is no God; they learn to do this quite will and boast themselves of being atheist. But even Voltaire, who tired himself of mocking the Scriptures and the church, when caught in a storm and in danger of death, is known to have spontaneously pray to God to deliver him. To say glibly, "There is no God," is the oppose all mankind, to deny the course of human history, and to contradict your own nature.
Customs, traditions, politics, commercial methods, art, and everything else in a state of flux; everything changes, but man, as a religious being, does not change. His religion may change, but he is still religious, and his conscience unceasingly testifies of his moral nature. Now since man is a moral and intellectual being, it is certain that a Higher than he has made him, who is also moral and intelligent. Man's moral nature (at all times and among all nations), his religious instincts, and his conscience all argue forcibly in favour of God's existence. His sense of moral duty may be weak of strong, defiled or pure, but is never totally absent. The only adequate explanation for all this is that God, the Supreme moral Being, who made us, also implanted this moral sense within every human being. No other explanation is satisfactory.
Humanity has an idea of a supreme being. This idea was frequently challenged (by atheistic idealogies, such as Communism) but never wiped away. While the concepts about God found among different cultures are varied, yet the idea remains.
Source: Truth For Today