Good clarification...Forgive me then if I seem pedantic, but isn't the Orthodox Church the oldest surviving Christian tradition? The Catholic church split off from them.

From https://www.oca.org/questions/history/the-original-christian-church

<<We Orthodox believe that we are the continuation of the ancient Orthodox Christian Church, that we trace our history back to Christ and the apostles, and that the Church was “formally” established on the day of Pentecost. The Roman Catholic Church placed itself outside of this fellowship when it broke off communion with us in the 11th century.>>

Of course, if we were too look further, the Theravada Buddhist claim an unbroken triton-- and institution of the monkshood (sangha) of 2500 years.