you know most of his teachings were taught 500 years earlier by Siddhārtha Gautama right? Read up Pancasila and it is almost the same teachings, but you don't consider yourself a buddhist?
Just because someone taught rightousness before another doesn't mean you "really" believe in the first.
Bhudda (Gautama) and Jesus both taught rightousness, happiness, and etc., this is the only similarity. The difference (and what's important) is how they applied this concept, applying it to two different foundations of belief.