Firstly, of course people can grow to believe in God without instruction, otherwise religion would never have arisen. We are all born agnostic. We don't know whether God exists or not.
Let's say there was something that wiped out all of humanity's knowledge, and we all became basically cavemen again. All science was lost, all literature was lost, all religion was lost.
Would we get science again? Yes. Would we get religion again? Again, yes.
But here's the difference.
Sooner or later, someone would come up with e=mc^2 again. But no one would ever come up with Christianity again.
We'd develop science again, and it would be the same, because science is real. But when we developed religion again, it would be a completely new style of religion.
Why do you suppose that is?
So first of all, the author says that God and evil both existing is completely logical, and yet then goes on to say that we are not able to say whether God has reasons to want there to be evil. This is inconsistent - if he knows God well enough to know that God actively WANTS evil to exist, then he doesn't get to turn around and say in the next sentence that we can't know the mind of God. Either you know the mind of God well enough to claim for a fact that God wants there to be evil, or you don't know the mind of God.
He then goes on to mention four things which, he claims, increase the likelihood of God wanting evil. The first is that God uses evil to bring people closer to him. I find this reasoning illogical, disturbing and inconsistent with reality. There are plenty of ways to bring people closer to you that don't require evil. I certainly don't allow evil things to happen to my daughter just because I want to have a closer relationship with her. And even if God worked like this, we'd expect to see Christians leading lives with less evil and misery than non-Christians, yet this isn't the case. In fact, the most secular countries are the ones with the highest standards of living, not the most religious.
He also makes the claim that evil is due to mankind's rebellion against God. Well, this contradicts his first point - is the evil caused by God as a way to bring us closer to him, or by naughty humans? And it also doesn't seem to take into account natural disasters that cause so much suffering. Or are we to believe that Iranian cleric who claimed
women wearing revealing clothes are the cause of earthquakes?
The thirds thing he mentions is that it doesn't matter if we suffer on Earth because we'll get an infinite reward after death. How this equates to God actively WANTING suffering and evil in this life is beyond me.
The fourth thing seems to be merely a rehash of the third thing.
His third argument for the existence of God is some attempt to use probability to convince us that God exists, and he doesn't do a very good job. All he does is assure us that when we look at everything, and he attempts to convince us with three pieces of evidence.
The first is that the universe exists. The first cause argument is weak and
has been debunked for a long time. The second is the
fine tuning argument, which likewise has been debunked (please note that the article I linked to here was written by a believer - even believers think that the fine tuning argument is a bad one!). And the third piece of evidence is the presence of objective morality. There is no such thing as objective morality. If there is, please tell me the objectively correct punishment for me to apply when my daughter sneaks out of the house in the middle of the night to meet with her friends, or for when she steals a chocolate from the shop? Can you do that? Or are you going to say that it all depends on the situation and since no two situations are the same, we can't decide on the appropriate punishment unless we know all the details, in which case you have just admitted that there is no objective morality after all. (After all, how can it be objective if it changes each and every time?)
In any case, the author of this article completely misses the one thing that proves him wrong - evil can still exist even if there is no God. It is impossible to claim that evil is proof of God if both God and not-God are able to account for it. And while he had to write this long article and still did a very bad job of explaining why there is evil despite God, I can give a very good explanation of why there is evil when there is not-God in a single sentence:
Some people are just jerks.
(I would have used much stronger language, but I would have been reprimanded for it. Feel free to use whatever profanity you think works best.)