Christ was a relatively modern man. Humans began farming during the Neolithic period, 25,000 years ago. It was the only way to deal with an increasing population and shrinking hunting grounds. Everyone had the same type O blood type until agriculture when type A developed.

I've been reading a rather strange book called "Eat Right 4 Your Type," where a naturopathic doctor postulates that type Os are suited for a very high protein diet as their blood type is paleolithic.