The "things" we are to believe about Jesus are found in the Nicene Creed. Interestingly enough, the Nicene Creed (and nearly the entire New Testament) was written specifically to refute Gnosticism, which had its own beliefs about Jesus. Gnosticism was a collection of loosely related belief systems that blended some teachings of both Christianity and Judaism with their own inherent beliefs. Generally, Gnostics believed in a superior invisible god who created all things invisible, including the human soul, while a lesser god, of sorts, created all things material. The first line of the Nicene Creed:
We believe in one God, the Father Almighty, Maker of all things visible and invisible.
The Gnostics also had their own teachings about Jesus. Those teachings were resoundingly rejected by Christian Orthodoxy early on, and the Creed was modified to reflect those orthodox beliefs. Such as:
He suffered, and the third day he rose again, ascended into heaven;
So to say that Jesus was merely a spirit being, had no corporeal body, and was never crucified would run afoul of Christian orthodoxy.
As another for-instance, everyone knows that Jesus walked on water. Almost everyone. I believe that the account of Jesus walking on water is an analog to the conversion of Peter. If it isn't it would be one heck of a coincidence. Now that is merely an opinion of mine of a non-essential nature.
So to answer your question, yes and no. There are some beliefs binding on all Christians regarding Jesus, and there is room for opinion on others. Provided that a person does not espouse a belief contradicting the teachings of the Church they remain orthodox.