At the time of Christ, Judaism was legal within the Roman Empire, and Jews were permitted to worship their religion. Christians were not covered by this arrangement, yet they had in the first century A.D. no Bible: the first book of the New Testament was not written until about 100 AD, though even that date this is not precisely known. It is deduced from its internal content. The other books were written even later. That is why in modern Bibles over half the content is from the Jewish tradition.