It is helpful to understand that God provides two distinct callings for every person on earth. The first is quite general, and everybody rejects it regardless of how religious he might be. Solomon writes in Proverbs 8:1-4:

Does not wisdom cry out, and understanding lift up her voice? She takes her stand on the top of the high hill, beside the way, where the paths meet. She cries out by the gates, at the entry of the city, at the entrance of the doors: "To you, O men, I call, and my voice is to the sons of men."

Here, the wisdom of God, personified as a woman, claims that the knowledge of God is readily available to mankind. Proverbs 1:20-26 affirms this:

Wisdom calls aloud outside; she raises her voice in the open squares. She cries out in the chief concourses, at the openings of the gates in the city she speaks her words: "How long, you simple ones, will you love simplicity? For scorners delight in their scorning, and fools hate knowledge. Turn at my rebuke: surely I will pour out my spirit on you; I will make my words known to you. Because I have called and you refused, I have stretched out my hand and no one regarded, because you disdained all my counsel and would have none of my rebuke, I also will laugh at your calamity; I will mock when your terror comes."

Again, God's wisdom is personified, and her testimony is that no one paid attention. All of mankind "disdained all my counsel, and would have none of my rebuke." With this in mind, recall what Paul writes in Romans 1:18-20:

For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who suppress the truth in unrighteousness, because what may be known of God is manifest in them, for God has shown it to them. For since the creation of the world His invisible attributes are clearly seen, being understood by the things that are made, even His eternal power and [divine nature], so that they are without excuse.

In other words, no man can stand before God and claim that he turned away from Him because God never provided any understanding of, not only His existence, but also many details of His power and works among men. How is this possible? Apart from the reality of creation, one reason is the ready availability of the Bible. Into how many languages and dialects have men translated it? Nearly everyone on earth can read or hear it in his own tongue!

Romans 2:14-15 presents yet another claim of God that blocks mankind's excuses:

. . . for when the Gentiles, who do not have the law, by nature do the things in the law, these, although not having the law, are a law to themselves, who show the work of the law written in their hearts, their conscience also bearing witness, and between themselves their thought accusing, or else excusing them. . . .

Deep within everyone, regardless of race or location, is a God-given awareness, a consciousness, not only of His existence, but even of some of the basics of what He requires, things written in God's biblical law. Despite all of this evidence, we universally reject Him. So thorough is mankind's rejection of God that, when He came as a man, we killed Him!