I'm really beginning to hate the book of Romans. There are many verses from it that I see theists often using so that they can claim knowledge over you in a debate. Just like Psalm 53:1, Romans 1:19-21 says that everyone knows god exists, and that atheists are really just deniers. Theists will throw this piece of rhetoric at you when then know they can't provide any real evidence that their god exists. So let me provide some justification on why I loath this verse.
First, if everyone knows the "truth" that the god of the Bible is real, then how come most gods that were fabricated are different from Yahweh? I mean, even today only 30 percent of the world believes Yahweh is real, and the other several billion theists alive have a wide range of deities they worship. It is far from "plain" that we all have an innate sense to know that the god of the Bible is real, as opposed to countless varieties of other gods.
Second, we have very good natural evolutionary reasons that can explain why we tend to believe in gods at all. I summarized this when I critiqued Alvin Plantinga's Evolutionary Argument Against Naturalism. Attributing agency to natural events seems to have been hard wired in us as it benefited our survival.
Third, the theist who holds to this doctrine in Romans fails to acknowledge the fact that some people are simply not religious. Some people like myself are who Blasé Pascal wrote of when I affirm that I am "so made that I cannot believe." I am a natural born skeptic; I've never had a religious inkling in me, ever. From the earliest age I could see through the lies of religion, and I never fell under its spells. That's something I am arrogantly proud of.
Fourth, the theist who outsources his evidence for god to the Bible fails to recognize that we atheists don't believe the Bible! This is something theists never seem to grasp. They think they can throw a few verses at us and it is going to make an effect. I can throw a verse at them from the "holy" Qur'an 3:85:
And whoever desires other than Islam as religion - never will it be accepted from him, and he, in the Hereafter, will be among the losers.
Is this verse going to make any Christian stop and think, "Woa. I better convert to Islam"? No! But countless stupid Christians think throwing a verse from the Bible at us is going to have that same effect with Christianity.
Finally, the theist who touts this rhetoric also fails to acknowledge that one can be a critical thinker who takes a good hard honest look at the evidence and concludes that Christianity is untenable, without being an evil "denier." I'd say there are some pretty damn good arguments and evidence to "excuse" oneself and deny Christianity and god's existence. The Christian can so easily see this in the falsity of Islam, but often their faith blinds them from seeing the very same flaws in their own religion. The Christian just projects their religious ways and emotional bias towards their own faith onto the atheist in the same way that the Muslim does. The Muslim has convinced himself that nothing can be more obvious than the truth of Islam, and so you must see it too. And if you deny this, it's only because you hate "Allah" and want to be your own boss. I can't tell you how many times I've heard this.
Theists are all alike.
I've recently been studying up on biblical criticism and I'm finding how flimsy the case for Christ really is, and how apologists have built their case on sand and faith.