There was a time when atheists had enough of a backbone to admit they have beliefs, just like everyone else. In the modern day, however, atheists have found a "clever" little way to escape accountability: "Atheism is just the lack of belief in gods". By claiming to merely lack belief in God, atheists believe they have shifted the burden of proof entirely to Theists, and that atheism is a logical default.
There are two major problems with this. The first is that a lack of belief is literally brainless. A rock lacks belief in God, because a rock, by its very nature, lacks belief at all. Thus, to claim that this new definition of atheism is the logical default is, itself, absurd.
But the more important problem is that none of us really lack belief in anything. To "lack" belief in anything is to accept an alternative explanation. Take, for example, Santa Claus. I "lack" belief in Santa Claus, but this lack of belief is not simply a lack of belief. I must come up with an alternative explanation for Santa Claus. How do the presents get under the tree every Christmas morning, if not Santa Claus? My mother even had a clever little trick: I was told that if the label on the present just said my name, but did not list who sent it, this present was given by Santa Claus himself.
But now I am grown, I "lack" belief in Santa Claus, but I do not lack belief about Santa Claus. My current belief is that when I went to sleep, my parents would go into their bedroom, where they had cleverly hidden all of the gifts, and wrap them up. They would then put them below the tree. The labels that said only my name? They were not from Santa, but from my parents.
I am even aware of how the myth of Santa Claus arose. He was actually a man known as Nicholas, or Saint Nicholas, a name that would eventually evolve into Santa Claus. He was known for his generosity, having inherited a large sum of money, which he would give to the poor, sometimes by dropping money down their chimneys under cover of darkness. The man, the myth, the legend, did exist. Parents would carry on his legacy for centuries to come.
Just as my "lack" of belief in Santa Claus inevitably requires a positive belief about Santa Claus, so also do atheists have beliefs about God. One of those beliefs is shown in the screenshot in the header image. In order to "lack" belief in God, atheists must come up with alternative explanations for how Theism originated. For Mark Twain, that explanation was that "religion originated when the first con man met the first fool." Or at least that's a clever way of saying religion is a giant con. That is a claim. The burden of proof is on Mark, and those who echo his beliefs, to prove it. But of course, they never can, because at least as far as Judeo Christianity goes, our origins story is far more solid than a con man meeting a fool.
There are other things atheists must believe in order to lack belief in God. Think of it this way: If I lack belief in builders and architects, that leaves a vacuum for beliefs about the origin of skyscrapers, cities, even my own house. This is why I like to say that one of the greatest pieces of evidence for Creationism is that of all the things they could have come up with as an alternative, they chose Evolution. Evolution is such a ridiculous belief that if the consequences for it were not so grave, I would not waste my time talking about it.
The one belief atheists must have about God is that Jesus was not Him. Atheists must come up with an alternative explanation for Jesus' birth, life, death and resurrection that does not include His divinity. Or, to put it as C.S. Lewis did, they must believe that Jesus was a liar, a lunatic, or the Lord. Some of them add a fourth option and claim He just didn't exist, but in all honesty, this is such a ridiculous conspiracy theory that I am forced by reason to... "lack belief in it".
The resurrection of Jesus not only proves that He was more than a mere con man, but it also provides the solution to our enmity with God. As sinners, we will do anything to avoid God, including deny His existence. But also as sinners, we are deserving of His wrath. None of us want that. But Jesus received that wrath on our behalf, and all it takes to receive the full benefits of that is to confess Him as Lord and believe God raised Him from the dead.
This hardly seems like the work of a con man. Aside from the literal impossibility of faking most of what Jesus did, even today, who benefits from it if it is not true? Jesus gained nothing. If it's not true, He died a painful death, and never received any worldly rewards before that. The Apostles gained nothing, they too lived a life of persecution that, for all but one Apostle, tradition tells us ended in martyrdom. The early Church gained nothing, they too were persecuted to the point of death or having to flee across the world. The insanity of claiming Christianity came about when a con man met a fool is completely unthinkable to me. Is this really what atheists believe? What other alternatives can they propose? As the saying goes, if you don't stand for something, you'll fall for anything. As such, I can say that atheism may not have begun with a con man, but it certainly began with a fool (Psalm 14:1).