Why is the Greek word Θεὸς in John 1:1c treated as a proper noun in English Translation?
John 1:1
New International Version In the beginning was the Word, and the Word was with God, and the Word was God.
New Living Translation In the beginning the Word already existed. The Word was with God, and the Word was God.
English Standard Version In the beginning was the Word, and the Word was with God, and the Word was God.
New American Standard Bible In the beginning was the Word, and the Word was with God, and the Word was God
I am specifically asking why the Greek word Θεὸς in John 1:1c treated as a "proper noun"(if the Greek is qualitative in sense) in English Translation?