While it is politically correct to say "I think" or I beleive, in my opinion logical argruments, based on true premises, have no need of this.
Anyway, you can't define Christianity as believing in Jesus.
James 2:19 - "You believe that there is one God. You do well. Even the demons believe--and tremble!"
Matthew 5:19 - "Whoever therefore breaks one of the least of these commandments, and teaches men so, shall be called least in the kingdom of heaven; but whoever does and teaches them, he shall be called great in the kingdom of heaven."
Matthew 7:15 "Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves."