The same reasons that Christians reject Islam by applying are also reasons that they can reject Christianity with or because of. Islam makes claims that mean Christians who reject Islam after Islam being presented fully to them will be sentenced to an eternity in Hell due to them being considered infidels by God. Still Christians do not become Muslims despite all this because there is not enough proof or enough evidence of the claims made by Islam about Christianity being a religion that should not be believed in or followed after Islam came to this world. Also, there isn’t enough proof or evidence of the claims made by Christianity as a religion. That kind of thinking is not applied by Christians when it comes to judging their own religion. It its either Islam is correct about its claims or not. And Islam and Christianity are both mutually exclusive, you cannot believe one of them without rejecting the other as a true religion from God, not because the idea itself is impossible and tolerance is something they both fail to adhere to or practice, but because both religions contain teachings that indicate that the other religion is wrong about a lot of its claimed to be inerrant and divinely inspired statements and principles. The reasons by which either of the two religions reject the other religion despite these strong claims, without them following the other religion anyway because it is too risky to ignore such huge threats that would make them suffer for an eternity in the after life could be applied to reject their own faith and religion in turn, but neither of them go this far. Whatever reasons a Christian is not a Muslim this Christian can also be a non-Christian (that is, leave Christianity, no longer be a Christian, become an Ex-Christian, abandon Christianity, or reject Christianity) because of them and this is also the case for any Muslim. (Whatever reasons a Muslim is not a Christian this same Muslim can also be a non-Muslim (that is, leave Islam, stop believing in or following Islam, become an ex-Muslim, reject Islam, or abandon Islam) because of them). This is just the religion they happened to favor and defend because it is their religion, (like in they happened to be Christians, Muslims, Jews, or be believers and followers of any religion) not because it is the religion they chose and carefully hand picked because they were convinced that this is the one true religion or that this religion is inspired from a God to people but only because this is the religion they found themselves believing in and following out of all other religions out there.

There is a problem here that many atheists or religious non-believers don’t seem to get. It is commonly stated by atheists that they just took it one God further. They rejected just another God in addition to all the gods rejected by most monotheists out there including Jews, Christians, and Muslims. This is not accurate simply because there is a barrier between believing that there are Supernatural beings responsible for all there is to be the way it is, and the absence of that supernatural being or those supernatural beings. Combining all the numerous Gods into one God changes nothing in terms of how everything there is originated or came to existence or how the universe and all that is in it run or are managed or work. Who controls everything? Not just who created everything. Who does what he wants and what he wills and can change anything he wants the way he wants? It is not just about the origin of the Universe and the origin of anything in the Universe. In atheism you change all your beliefs and explanations for all of that, and you almost change your beliefs and explanations of everything there is. And this requires a massive increase in the knowledge of the atheist person to be able to become an atheist who is not just ignorant to why he should have been religious, but someone who understood that it turned out that atheism is the truth and that atheism explains everything. This does not occur in the transfer from polytheism to monotheism. Just canceling a large number of Gods to claim that only one God does all their jobs and responsibilities and work alone on his own without assistance or interference from any other entity whatsoever. So by understanding this, you now know that I do not believe that Atheism is just taking the process of canceling Gods one God further, it annihilates the concept of the necessity and the actual existence of any God whatsoever. And that in and of itself is an active positive affirmation and belief, not just the lack of one. Yes, anyone who doesn’t believe in God or lacks the belief in God is an Atheist, but atheism cannot be reached without actively rejecting the entirety of any kind of theistic claim to the necessity of the belief in the existence of any God, albeit following the religion delivered from this God to humanity for all time and worshiping this God or those Gods.

It is not that it is bad to follow the good stuff that is in The Bible or The Koran, if there is any. It is that it is bad to believe that this good stuff is the literal and actual inerrant word of a God that was divinely inspired to one human or to some humans who transferred this light to the entirety of humans or some group of people or community of people. It is that we should believe not just in that content and these teachings and principles but we should believe that this content and that these teachings and principles are what God told us to believe in and follow, or else we will suffer the consequences of disobeying God.