Trinity,a question

Okay, don't call me a heretic when you hear this question (if anyone even reads this anymore). This is a serious question, but it questions something that is so ingrained, at least in me. Here it is;

How important is it to believe in the doctrine of the Trinity?

Let me explain. Mainline Christianity basically says that it is very important, that our salvation hinges on it. Jehovah Witnesses and Mormons both do not believe this doctrine the same way "we" do. And let me emphasis, I do believe this doctrine, I do believe that Jesus is God, and I do believe this can be found in the Bible (John 1 for example). But, at the same time, I see where someone else might not come to the same conclusion. It really is a hard, humanly speaking, doctrine to understand. Most people cannot explain this doctrine in a way that is the least bit convincing. The Bible doesn't spell it out in plain language and it never emphasis' it as an "essential" doctrine. In fact, there are many other things that are emphasized more that we've disregarded, i.e.: repentance(really turning from your sin(Luke 13:2)), baptism (Acts 2:38), selling your possessions (Luke 14:33), and the list could go on.

So, why has the doctrine of the Trinity been made so important? If someone believes that Christ is the Son of God, that He died for their sins, and they except this personally and live their lives accordingly, but don't believe that Jesus and God were one, the same way I do, will they go to heaven? The way I've been taught, the answer would be "NO". But now, I'm not sure. How important is our overall understanding of these things? I mean there are basic truths, but how much beyond that are we required to fully comprehend? Do you understand why Jesus had to be baptized with the Holy Spirit or baptized at all (Mt 3:16)? How about this verse:

"The Child (Jesus) continued to grow and become strong, increasing in wisdom; and the grace of God was upon Him." (Luke 2:40, NASB95)[1]

Was Jesus all knowing, always? Is it essential for me to know that answer? Again, how important is it to believe in the doctrine of the Trinity and why?

I'd love feedback if anyone is still out there (anonymous is fine).

^[1] New American Standard Bible : 1995 update. 1995. The Lockman Foundation: LaHabra, CA