My first question is, does the Chaldean Church accept the phrase, "One of the Trinity suffered in the flesh?"
Salpy,
Being in the Catholic Communion, we don’t consider that phrase as heresy, since it was accepted as orthodox at Constantinople II, but we would re-express it like this:
One of the Trinity became Man and suffered.The Chaldean version of the Creed says: “. . . one Lord, Jesus Christ, the
only Son of God . . . descended from heaven, betook a body by the power of the Holy Spirit, was conceived and born of the Virgin Mary and
became man, who suffered and was crucified in the days of Pontius Pilate, who died . . .”
So you see, the Son, who is one
Qnoma of the Trinity, became man and suffered.
My second question is, does the Chaldean Church teach that Christ's divinity and humanity ever seperated?
No. The Union of the Son and the human
Qnoma was inseparable. Christ was always One Person, His Divinity and His Humanity remained inseparable.
For example, on the Cross, when Christ said, "My God, why hast thou forsaken me?" Do you believe that at that moment Christ's divinity left Him and that is why He said that?
No. The one Person of the Union, the Lord Jesus Christ, cried that statement out as Man, not because a separation of the Union has occurred, but because the one Christ does certain things as God and certain things as Man.
Here is how Mar Narsai, a father of the Church of the East, describes Christ in the passion/death/resurrection:
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the attendants seized Him and bound His hands, as Man;
and He healed the ear that Simon cut off, as God.
He stood in the place of judgement and bore insult, as Man;
and He declared that He is about to come in glory, as God.
He bore His Cross upon His shoulder, as Man;
and He revealed and announced the destruction of Zion, as God.
He was hanged upon the wood and endured the passion, as Man;
and He shook the earth and darkened the sun, as God.
Nails were driven into His body, as Man;
and He opened the graves and quickened the dead, as God.
He cried out upon the Cross 'My God, My God,' as Man;and promised Paradise to the thief, as God.
His side was pierced with a spear, as Man;
and His nod rent the temple veil, as God.
They embalmed His body and He was buried in the earth, as Man;
and He raised up His temple by His mighty power, as God.
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By the way, in the Peshitta, the way to translate the phrase in Matt. 27:46 (
ܐܝܠ ܐܝܠ ܠܡܢܐ ܫܒܩܬܢܝ) might be better done in English like this: “[my]God, [my]God, why have you spared me”. This is how it is translated by Assyrian scholar Paul Younan. In my opinion, this may be a better translation than the usual “forsaken me” translation.
Also, Jesus was utilizing Psalm 22:1 when he cried this out.
Thanks for the questions

God bless,
Rony