The statement "Christianity was outlawed until Emperor Constantine converted" is true. Christianity was indeed illegal in the Roman Empire until Constantine the Great converted to Christianity and issued the Edict of Milan in 313 AD, which granted religious tolerance to Christians.
The other statements are false:
- Judaism did not begin as a branch of Christianity; rather, Christianity emerged from Judaism.
- The Ketuvim is a section of the Hebrew Bible, but it is not a section in the Christian Holy Bible.
- Pesach (Passover) is a major Jewish holiday, not a Christian one.