Hi Drew,
I now believe because I could not explain all the parallels between Yahweh of the old testament and Jesus of the new testament without the trinity. It was the only way I could resolve the fact that Yahweh said in the old testament that he is the only Savior and the only God, no God before him or after him. He also said every knee would bow before him and that there would be One Lord. These are in Isaiah. Then in Philippians it says every knee will bow before Jesus and confess that he is Lord to the glory of the father. In the old testament, Yahweh said he would be betrayed for 30 pieces of silver. In the new testament, it is Jesus that is betrayed for 30 pieces of silver. In Isaiah, Yahweh says he is the First and the Last, in Revelation the first chapter and the last chapter, Jesus says he is the First and the Last. In Acts, Ananias is accused of lying to the Holy Spirit, then farther down in the passage, it says he lied to God. How can you lie to something that is only an active force? Why would the new testament say we need to be baptized in the NAME (singular) of the Father, Son, and Holy Spirit? There are tons of other scripture connections I found which made me believe the trinity is in fact the only explanation that resolved it for me. That God has shown himself in 3 ways or manifestations all with different functions for the purpose of salvation. It confused me at first but now it doesn't so much anymore. I also believe God is mysterious and isn't like anything we have ever seen or experienced. We only really understand what we have already seen.
I compare it to someone being born blind and never being able to experience sight. I can't imagine trying to explain color to them or trying to explain what having sight is like, it would be impossible. Same with hearing. We only understand based on what we have already seen or experienced.
Sorry to go on but I find this subject fascinating. Especially since I was raised a JW and was the biggest one to walk around and say the trinity was nuts and made no sense. And now I totally believe it.
Thanks for asking,
NowImfree