IMO in the search for true religion I think it's a fair call to eliminate all religions other than Islam, Christianity and Judaism immediately (sorry) because these religions are supported by so much evidence, however obviously I believe it's necessary to eliminate further.
Once you make the assumption that the Bible is a book inspired of God - which those 3 major religions accept to varying degrees, it becomes easier to eliminate.
You can throw out Judaism (sorry) because they were fairly well abandoned as proclaimed by so many of their prophets and the coming of Jesus to replace the old covenant with the new covenant (replacing mosaic law and Jewish system with system open to all). However, at one point Judaism was the true religion as selected by God. This has changed. Upon this foundation we can ascertain one certain long held Jewish doctrine which is very important.
There is no trinity, thus trinitarian Christianity is eliminated (sorry). Thus, Islam and non-Trinitarian Christanity are considered since they believe in One God. (Deuteronomy 6:4)
Now, since both these two groups accept Jesus to varying extents we can establish two things:
1) False prophets will arise. Matthew 24:24 - direct quote from Jesus here.
Jesus says false prophets will arise so as to mislead many. Sorry, Islam but you are many, are you not? and as Jesus said, those false prophets have "performed great signs and wonders". So it's not like Muslims have no basis for their belief, but according to Jesus, Mohammed is a false prophet (sorry). Also Joseph Smith by that is a false prophet. (sorry)
2) Jesus said he was the son of God. He said this many times and was the reason he was prosecuted and sentenced to death by crucifixion by the Jewish Sanhedrin court.
Jesus was crucified. I know that some in Islam deny this, however the historical evidence is clear. Roman historians, Jewish historians, Christian historians, Greek historians, Pagan historians - all of them say Jesus was crucified. This forms the basis of the ransom sacrifice that Jesus gave.
Hence, Jesus and Islam contradict fundamentally. Since Islam accepts Jesus, but Jesus rejects Islam and Jesus was earlier, Jesus can be accepted over Islam. (sorry)
While this is a fairly crude examination of the facts, these are absolutely fundamental facts and their truth makes or breaks a religion.
The winner is: Non-Trinitarian Christianity
I heard an illustration once which you can use to discern truth. Jim and John are two fishermen and your friends. They approach you after a fishing session and tell you that Jim caught a large fish. John shows you how big it is by indicating with his hands that it was about 50 cm. Jim disagrees, he shows you with his hands that it was about 80 cm! How do you find truth. Well you ask them to show you the fish and you measure it with your ruler.
The same is true with any religion who looks to the bible for truth. (Of course Islam says that the bible has been mistranslated into English and is somehow corrupt, but IMO is quite a copout.) Ask them to show you for a simple biblical explanation for their version of truth. A simple examination of the Bible will show you that hell doesn't exist, there is no immortal soul - when we die we're dead, there is no trinity, there is a verifiable truth which is available today (Daniel 12:3,4), there will be an end to suffering soon, God made people to live forever on earth (e.g. Adam and Eve original purpose), and there is an acceptable reason for why suffering occurs today which no mainstream religion today has found (not telling but I know
). This is my take on the whole religion thing.