Original: It traces its origins to the See of Seleucia-Ctesiphon in central Mesopotamia , which tradition holds was founded by Saint Thomas the Apostle ( Tooma Shlikha ) as well as Saint Mari and Saint Addai in 33 A.D. as asserted in the Doctrine of Addai .
Simplified: It traces its origins to the See of Seleucia-Ctesiphon , started by Saint Thomas the Apostle as well as Saint Mari and Addai as shown in the Doctrine of Addai .