Debating the Exisitence of God

I went to a debate about God last night. On one side, there was an atheist and former pastor, on the other side was a Christian apologist. I usually find these types of things pointless. In one sense, I guess it was-My mind wasn't really changed by the debate. I went in believing what the Scriptures say about Jesus (that He was born of a virgin, performed miracles, died on the cross taking the penalty for man's sins, and rose again) and I left believing the same thing. What I did come out of it with is an understanding of the importance of understanding what you believe in. The atheist guy used to be a Christian. He was a pastor for 19 years, and yet I got the feeling that during that time, he didn't understand his own faith, which is probably why he lost it. For example, on the doctrine of the Trinity, he claimed that the main verses used to support it is 1 John 5:7-8. He correctly pointed out that this verse is changed in late manuscripts to read "There are three that testify in heaven the Father, the Son and the Holy Spirit. These three are one," rather than "For there are three that testify: the Spirit and the water and the blood; and the three are in agreement." In reality, as far as I know (which admittedly isn't much) there is no one verse in the Bible that says "yes, God is Triune." However, there are many verses that clearly indicate that 1)The Father is God 2) Jesus is God and 3) The Holy Spirit is God. How is this not three different gods? Read Deut. 6:4.

I may post more on this later.