Assyrian Church of the East

The Apostolic Catholic Assyrian Church of the East (Syriac: ܥܕܬܐ ܩܕܝܫܬܐ ܘܫܠܝܚܝܬܐ ܩܬܘܠܝܩܝ ܕܡܕܢܚܐ ܕܐܬܘܪ̈ܝܐ, ‘Ittā Qaddishtā wa-Shlikhāitā Qattoliqi d-Madnĕkhā d-Āturāyē; Arabic: كنيسة المشرق الآشورية الرسولية الكاثوليكية المقدّسة) under H.H. Mar Dinkha IV is a Christian church that traces its origins to the See of Seleucia-Ctesiphon, said to be founded by Saint Thomas the Apostle as well as Saint Mari and Addai as evidenced in the Doctrine of Addai. It sometimes calls itself the Assyrian Orthodox Church, and is sometimes mistakenly thought to be an Oriental Orthodox body. The usage of the term "Orthodox" is not to be found in the service books of the church nor is it in any official correspondence but a late and confusing usage of a term that belongs to Eastern Orthodox and Oriental Orthodoxy churches.