The simple reality is that if there's a God (and I believe there is) then He's allowed not only different religions (many of them false) but also the different flavours of religion. Now we can only speculate why but I suspect the reason is that God demands that we REALLY want to know the truth rather than have it handed to us.
The bible tells us that we cannot find the truth on our own, no matter how hard we look but that if we sincerely seek the truth then God will meet us and show it to us... and so the simple answer to your question is .....
...if you really want the truth, seek it out with all your heart..........
It's not about feeling good, although that might be part
it's not about intellectual argument, although that will take shape in the process
it's not about others, although others might help they also might hinder
it's not about anything but you and God.
..that said here's my view...
We could investigate and evaluate every book in order to decide. However, not only would this be difficult but it would also be extremely time consuming.
Fortunately there is the possible option of shortening this process by determine which is the most likely. If this turns out to be true then we save time and effort. If not then we move to the next most likely and similarly we can save time and effort (just not as much).
Nearly all religions have God as a good force and another entity as a bad force. The object of the bad force is usually to do bad, get people to do bad and to make sure people don’t find the good God.
The latter element provides us with good logical possibilities.
If the evil force is trying to prevent us finding the good God, it will use more of its resources, strategies and tactics on hiding the true book and true religion than the false ones it created itself. One of the most effective strategies to lead people astray (and indeed to sell a lie) is to keep as near to the truth as possible with subtle lies that are sufficient to not get the important part of the truth.
Hence the most likely true religion will be the one with the most offshoots, variations and conflicting claims for truthful revelation from God.
That clearly is Christianity.
In terms of evaluating Christianity then…
So far logic and reason has deduced Christianity is the most likely truth. However, logic and reason will only get you so far especially if there’s a God. That’s because God being so complex is never going to be understood in the small space between our ears. It’s logically not possible!
The process from here on is going to take time and effort. However, if you start reading the bible to test it and do so with an open mind and heart the bible tells us God will meet with you. (seek and ye shall find). The trick is to be open. There’s nothing wrong with questions or doubts. Just ask but open and the truth will set you free.
PS There’s no shortcut to doing the evaluation work yourself. However, for what it’s worth my view is … JWs and Mormons are weird and quite obviously wrong, Catholics have allowed the devil to influence and Orthodox is stuck in prideful rituals. –even if they’re nice people! There are a whole load of other Christian flavours (Baptist, Evangelical, Pentecostal, etc.) that basically believe all the main things but have different emphasis.
a note on denominations and why there are so many in Christianity...The fact that there are many religions and many types of Christianity is for me, evidence that for whatever reason God allows confusion or differences in the matter of faith.
Personally I suspect the reason is that God wants us to want to find Him, love Him, etc. If it was obvious then not only would it erode our free will but it would also mean we’d likely take God and truth for granted. More than that, if being absolutely accurate in faith, why does God allow many different denominations and associated differences in belief. My view is that God is less interested in us believing everything perfectly and more interested in us serving Him in what area or capacity He directs. This should not be surprising since we acknowledge no man is sinless or perfect. That being the case how can anyone find and hold fast to perfect faith (i.e. no error).
I have noted that in the past many Christian denominations have resulted from a similar pattern…. God decides to anoint a man and set him apart from others in the faith. This man steps up to the plate, communicates God’s message and attracts a following. Generally this following is not well received by existing denominations (blindness, envy, jealousy, etc). The following grows and the man sets up leaders. The man dies but the new denomination has been established. The leaders keep the man’s work going but each generation of leaders becomes more and more human minded and less Godly minded. God raises up another man and the process continues. (examples include Methodist, Wesley, Calvary Chapel, Chuck Smith, etc.)
What I find interesting is that God seems to be using people from every denomination and that there are true believers in all the main branches of Christianity. I have to say I suspect there are a lot of people attended all branches of Christianity who aren’t believers too! This being true, it means that most Christian denominations have born again believers in them that collectively make up Christ's church… and the evidence for this? Read the bible and look at the early churches, their arguments, their differences, etc and yet they are regarded as one church…. And if you think that's all in the past, read Revelation and read about the seven churches and see that it's also the future!