One's Religion Is a Choice. It Is Not an Innate Characteristic of Anyone.
Unlike skin color, sex, sexual orientation, gender, or birthplace, one may choose one's own religion freely. That sets religious belief apart from inborn characteristics. While many people are indoctrinated into a religious belief system, it is entirely possible to change one's beliefs or to abandon religious belief altogether. Evidence of that is everywhere.
Intolerance or bigotry are directed at inborn characteristics of people, through classification. Simply not believing in some religion is in no way intolerant of anyone. Actively stating that a particular religion or deity is false is also not intolerant of anyone. It is not bigotry, either. It is simply stating one's own belief about a set of beliefs. You are welcome to say that you believe in a deity or deities and that my disbelief is incorrect.
Now, some religion might consider a negative opinion about it or dismissal of its deity or deities to be blasphemy. Blasphemy is not intolerance. It is simply disbelief or outright dismissal of the validity of a particular religious belief or deities. Most Christians, for example, do not believe that the Hindu pantheon of deities are truly of a divine nature. To a Hindu, that is blasphemy, yet most Christians believe and declare that only their deity is a deity, by definition.
I think and will declare that all deities are figments of the human imagination. I therefore blaspheme all religions that worship deities. I do not, however, condemn all believers in those deities. I simply do not believe as they do. I am not intolerant of them. I simply don't believe the deities they worship are real. In that, I am similar to a Christian who dismisses the divinity of Hindu gods. I just dismiss them all as imaginary.
If people decide that they believe in a deity and worship that deity, I don't really care. That is, or should be, irrelevant to my life. If they attempt to foist off their deity on me, however, I will reject their attempt. I have made my decision, after due consideration, and have no deities to worship. I'll be happy, though, not to obstruct your worship of some deity, as long as it doesn't interfere unduly with my life or the lives of others. I'm not intolerant of your religious beliefs, though. I just think they're superstitious, but what you believe is none of my business, really. The problem arises when you insist that I or others should or must believe as you do.
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I will defer to your expertise on this!!!!
Here's how I look at that: What we know (or think we know) is what we have learned or have been exposed to and accepted. At about age 16, I began to choose my own sources of information, based on my particular interests at any given time. I no longer accepted the choices of others regarding what I fed my brain.
I soon recognized that reading the ideas of others was also fraught with the danger of accepting those ideas as my own, so I took in information from a very broad range of sources, and on a very broad range of subjects. I considered each exploration as a logical challenge, retaining what made sense, and rejecting the rest.
From that time forward, I have been an autodidact. While I've taken courses at various schools and have a BA degree (English,) I never let my directed studies interfere with my own more random, but, self-directed, acquisition of knowledge. That was almost sixty years ago. I remember pretty much all of what I have learned. So, I doubt very much that I will revert back to any earlier stage. In fact, I continue to learn new things, moving on to different subject areas on a regular basis. Am I likely to become a theist? That seems to me to be an impossible thing. I finished that stage of exploration decades ago.
To what end was all of that? To no end at all. The process continues, and will until it does not. That's the life I have chosen. It is my own. Is it unique? Well, pretty much, since I consider each person to be unique. Is what I have learned correct? As far as my reason has been able to assess it, yes, it is. I have discarded more than I have retained, when it failed to convince.
Of what use is it? Well, when my wife, working on a word puzzle, asks me for a 9-letter word for a flightless bird, I can immediately tell her that the word is "cassowary." That is the only flightless bird with nine letters in its name. When she asks me how I know that, I can tell her the title of a book I read at 10 years of age that taught me that word. I have learned, though, that she doesn't particularly want to hear about its size, weight, the bright colors on its neck, nor its habitat or eating habits. It pleases me, somehow, to know those things.
How will it all end? I have no idea, except that I will cease to exist at some point. Life's a one-way trip. I might as well enjoy it. 
Fearing death is a survival instinct as is hope for a different outcome. It didn't take long before some began manipulating other people with the conveniently unverifiable promise of immortality. Profit and power comes to those who are successful at it.
