Having read the comments, most people are dealing with the relationship on a here and now basis. My piece of advice is to do with the future - what would you envisage telling your children ? That is the real deal breaker if you are going to have opposing views, think about what you would teach the next generation. Even if you never have them, it does help to show how closely allied your values are if you ask this question. Me and my other half have opposing political views, but are totally on the same sheet as regards morals, gods and religions. As a result, our children have had a secular up bringing that we both weighed in on.
Just another angle on how far you are willing to compromise.
Personally, he does not seem to use rational logic to examine his belief system......so what else would he swallow ?

Both of you might look into theological noncognitivism or ignosticism, the disbelief that the row of alphabet letteds "God", "Allah", "Yahweh" have any conceptual meaning at all. You might discover that neither theists, atheists, nor agnostics have it right, because you and your boyfriend both realize that neither of you has any mental concept whatever of anything that "God" could refer to.

Your boyfriend isn't really an agnostic. It sounds like he is religious but wants it his way. People like him are why we have so damned many denominations of Christianity.
In my earlier life I wanted to know all things. Christians claim that they know. At least they "know the plan" and know how things are likely to turn out. As an atheist I cannot know. There is no possible way I can know and it is OK not to know. Without evidence I cannot know much of anything.

Agnosticism is of the essence of science, whether ancient or modern. It simply means that humans shall not say he knows or believes that which he has no scientific grounds for professing to know or believe. Thomas Henry Huxley. With that said, your BF is not an agnostic.
I also live in the Bible belt and trust me; 99.9% of the population is Christian. What is thought-provoking is the fact that Christians come in several alliances with altered theories. There are even, GOOD Christians and all other. Disconcerting is the conception that ONLY their VIEWS and analysis of the Bible are accurate and precise. Perhaps what annoys me most is numerous Christians lie (e.g. TRUMP) and these individuals want your trust. Advertising expresses; hire this person because they are a GOOD Christian.
Regarding the BF, he may be a nice guy, handsome, a good lover, but all of this not enough. He was exposed to radical religious beliefs for childhood to adulthood. Radical in the sense that the most pious Christians are devoted to Catholicism and the likes of Jehovah witness. They will never change their religious convictions and should a disagreement occur during your association; you will be the one cast out, demeaned. or offended.

I do not respect superstitious (religious) people so a potential partner that is religious is a not an option as I value truth (based on facts not faith (belief without evidence)) and respect.

This may be worth listening to.

We have wider question here and it doesn't just concern the lasses BF.
Agnostics sit on the fence so to speak. They're opportunists. If there was a god they may get 'forgiveness' where as if there was a god us poor athiests would just have to indulge in unending orgies in the fires of hell (stock up on the 50+ sunscreen lotion) just in case. Would definitely be more fun than floating around with sexless angels.

Seems to me there are a couple of different themes going on in this thread, one being the difference between an agnostic and an athiest and one being about how differences come between being a couple. I would like to address the one I think you really hoped to get some insight on (that being how can you have a relationship if you believe different things) while eluding to the other.

First of all - you can have a relationship that works if both of you are determined to do it. It won't be easy. Differences tend to come between people. What I think you have to do is remember that some differences involve what people believe and some involve what they know. When we have evidence of something in gives us knowledge of it. Belief is a choice based on personal experience.

As an example, if you know your boyfriend is 25 years older than you - and you have evidence of that because of a birth certificate, driver's license, or lines on his face - then it is something you know and you can't change it. You have to accept it.

Then there is what you believe. Belief is not based on evidence. It is based on personal experience. You believe things because in your experience it makes sense to you. If you believe you can make a relationship work and he believes it too then it is because you have some shared experience leading you to believe you can do it. If you believe you can't overcome differences and he believes you can overcome them, then you have a different set of beliefs regarding your relationship. But you don't know for sure if your relationship will work out. There is no evidence (yet, anyway). So here is where you can use your beliefs to shape your reality - or the evidence of what will be when you are in the future looking back on it. Either it will work because you believe you can make it work and that motivates you to do it. Or - it won't work because you believe the differences will come between you. The key to overcoming differences is an understanding of what belief is.

Now as to what flat-earthers believe in the face of evidence - that's a whole other story

I have no idea why he claims to be agnostic. Seems pretty clear he's a believer.

Atheism is stronger in definition because it comes from the premise there is no logical explanation for the existence of a supreme being. Equatable to santa claus, the tooth fairy, leprechauns, sprites, demons etc. I don't need to look for proof or lack of of a substance that has no relevance to my life whatsoever. Logic not arrogance influences my thinking ?

You are trying to have a relationship with someone less educated, and (it seems) less intelligent then you. There is nothing wrong with that, as long as you accept it from the outset. You can either allow this to be a point of contention between you, or just accept that he simply isnt very bright, and admire/love him for what ever else it is that he brings to the relationship.

I'm reminded of the family guy episode with James Woods "oh, piece of candy. ? Oh piece of candy ? oh piece of candy ? oh piece of candy ?"
Leave little morsels of info in various ways. I'm a fan of comedy to convey the info. Stand ups, or YouTube videos playing in the background while he's busy with something else, might peek his curiosity.
Good luck