I don't know if this has been done before and I know it should be in Religion but ive chosen to put it here as I would like to know other ways people rationalise (besides religion) that God does exist. I have many reasons to agree with his existence because of religion but personally im a rational thinker, I put i t down to probability 50/50 he either does or doesnt.
It's ironic that whilst you claim to be a rational thinker in the same breath you show lack thereof!

Rational thought is (or should) be governed by or showing evidence of clear sensible thinking and judgment, based on reason rather than emotion or prejudice.
You're asking for ways people 'rationalise' existence in God in ways other than Religion. A contradiction, since religion itself is defined as a system of belief/faith. Whatever you say about your thoughts on God
is a 'religious' opinion, could be a personal religious opinion rather than one from an organised religion, nevertheless it is a religious opinion based on faith. Even your '50/50 theory' was conceived by a Christian mathematician, some Muslim scholars of Kalam also posited this.
Let's just say you meant to separate between opinions from an established religion and other. What is the logic in doing that? What "rational" significance is there in dichotomizing betweeen opinions held by a large group of people (which is effectively all what an established religion is) and opinions held by relatively smaller numbers?
The second fatal flaw in your reasoning is that you asked for ways to rationalise the existence of God, then offered your reason which does not and is not intended for rationalising the existence of God! Your assertion that you fear God and you cannot fear something that doesn't exist - is incorrect. You can have an irrational fear of something. Some people fear the 'boogyman', that does not necessarily increase the likelyhood of his existence.
Thing is by believing its a win/win situation, if he does exist and if you believe in him and lead a good life, you get to go to heaven

If he doesnt exist, well you lead a good life thinking you will be going to heaven and therefore die happy

However if you don't believe and he does exist, I dont think he would be mighty pleased with you
Pascals wager does not give reason for the existence of God, it is a reason why you choose to believe in a God. In my opinion a very weak reason to believe in God at that. The great saint Rabia al-Adawiyya once made the du'a "Oh Allah if I worship you in fear of hell, burn me in hell. If I worship you hoping for paradise then exclude me from it, if I worship You for Your own sake then grudge me not Your Everlasting Beauty". Her iman was on another level but just to illustrate, experientially iman can differ vastly between people, so much so what one person calls iman would be cosidered kufr by another.
Proving the existence of God is a logical fallacy, depending on your definition of God. Allah exists beyond time, space and matter. He is not a part of creation, so how do you suppose to prove His existence using creation? It's like asking bacteria in a dish to prove the existence of man. People who ask for proof of existence of God have missed the point completely, even the Muslims who attempt to prove the existence of God using Aristetolian logic (causality etc) are kind of missing the point. None of that proves the existence of God, they just show it is not irrational to believe in a God.
Any belief in God derived by the physical senses or by a mind is founded on precarious ground. To know God first you must know what you are. If you believe you are just body and mind then those are the only instruments you have to know Him, if you believe you have a soul then you have a whole other dimension to your perception of reality. The soul is the most God-like thing in creation, it is everlasting (not independent of God though), is in the world but not from it. Elusive to our senses but we know it exists.
Allah put signs in the world - ayat, that point to Him. The signs are everywhere, but why do some see the signs and some don't? Why do some see the signs and it actually confirms their disbelief while for many it is just an undeniable fact that there is a God? It means one thing, its not about the signs, they are the same, it is our perception of them. The senses see the signs, the mind processes the information (like a computer) but its the soul that either accepts or rejects. If we can have weak senses, and some people have weak minds, there is no doubt there are weak souls out there, many comatose. Allah describes them as deaf, dumb and blind - not an issue of intelligence, it is arrogance that is the root of kufr.
Atheism is as much a 'faith' as any other religion because the existence of God cannot be proved or disproved empirically. Asking 'prove to me God exists' carries as much rational weight as asking 'prove to me God doesn't exist'. But by asking the former you are beginning by intimating the non-existence of God, whilst belief in God is innate, from our primordial nature (fitra). It is disbelief that is "unnatural".