They surely disbelieve who say: Lo! Allah is the third of three; when there is no God save the One God. If they desist not from so saying a painful doom will fall on those of them who disbelieve (Sura 5:73)

The order he said is as clear as crystal 1. son, 2. mother, 3. father/Allah
Look carefully, "Did you say take you and your mother for two gods besides me?" 1, 2 & the third of 3. I know you can see this so being obtuse or using semantics is lame and cannot get you out of it or make the verse work the way you want to believe.

Allah said the third not a third of three. Besides, if someone wanted to say a third of the whole, there is not a need to say a third of three. Just saying a third is sufficient to know that a third is one third of three parts, but clearly he didn't say a third ; he said the third. Semantics doesn't work friend, nice try. So you could've convince me and no cigar for you. Again, Catholicism and Biblical Christianity does not believe God is a third. So who was Allah referring to. No one believes in the inferred trinity described by Islam's god or messenger. We all believe God is one. Jesus is not a third of God; He is the word of God, and God is the Holy Spirit!

No one can explain God's essences or how He can make His word and Holiness persons which are not thirds, but fully God. It is other earthly or worldly. God cannot be explained by finite beings such as ourselves or incorrect math formulas such as 1+1+1=1. Muslims have no good reason to reject God's tri unity. Just like you accept Allah is one when he say we have sent down the Torah as the royal we, we accept God saying let us make man in our image and likeness as the royal us. I am a soul, I have a body and a spirit and yet I am one not three. I cannot make my word a person or my spirit one, but God is not limited. Man is limited and limited in understanding. You have no reason to reject perfect monotheism and the perfect unity of God expressed in His Son (The Word) and Spirit. The Jews and Christians were saying God is and was one way before Islam's prophet was born. It is an imperfectly borrowed concept, IMHO, just as is the virgin birth of Jesus which came from the NT Bible first!

Peace unto you