Who is He?

Ever since I became a Christian, I have a lot of doubts. The biggest is probably about Jesus. I believe in God and He is in control. He has indeed showed me His power and grace. But what about Jesus? I know the Scripture mentioned that there is a Messiah coming. But different religions have different takes on this. From time to time, I struggled between believing and not. I asked my friends before, how do we know what we believe is not a cult. I know a lot of cults is based on Christianity and diversified from it. They took a section of bible and interpreted it differently. How do I know I am following the correct one? My friend said Christian believe in trinity, the Father, the Son and the Holy Spirit. But how do I know Jesus is really the Son? How do I know the other interpretation is not correct? They all believe in God. How can I be sure they are not right? I am all confused and lost. I don't know what to do. I am reading a book my friend lend me called "The Jesus I Never Knew". May be that would put things into perspective for me again.

PS. While writing this blog, I search online and run into this site, everystudent.com. How could I forget what I read before? How could I keep having doubts?