Arius grappled with the notion of the trinity, a notably difficult doctrine (as is any doctrine dealing with the nature of an infinite God, difficult for our finite minds :).
His false teachings led to the Council of Nicaea (and Nicene Creed, which actually came from the Council of Constantinople). The Nicene Creed remains today the fundamental point of agreement for orthodox Christians.
The notion that Jesus is not God creates several theological problems:
- Messianic prophecies attribute to the Messiah God-like properties (Isaiah 9:6)
- If Jesus is only a man, how is it He is without sin? (Romans 3:23)
- If Jesus is not God, but somehow a truly "good" man; how does His death demonstrate God's love?
- Why does Jesus refer to Himself as eternal, and "I AM" (God's name)? (John 8:58)
- Why does Jesus take the authority of God to Himself (forgiveness of sins)? (Matthew 9:2, etc.)
"Jesus was specially created" - If Jesus was specially created without sin (but not as God incarnate), why aren't we all?
"Jesus wasn't meant to die like that, it was just a misunderstanding" - This is a really poisonous idea to hold. I know, I used to believe it! (Thanks "Slaughterhouse Five", not!)
"Jesus referred to Himself as God, because we can all be God" - This is really scary. Mostly because it is so prevalent...