Your grammar is weak.
What is the purpose of a comma? To separate elements in a sentence. In other words, if you remove any portion between two commas, you still get a coherent sentence that conveys the full meaning, except that only one element is missing.
So, let's break down the sentence, shall we?
But the plan of salvation also includes those who acknowledge the Creator.
In the first place amongst these there are the Mohammedans,
who,
professing to hold the faith of Abraham,
along with us adore the one and merciful God, who on the last day will judge mankind.
Alright, now what is the "church" asserting here? Let's remove only one element of the statement:
But the plan of salvation also includes those who acknowledge the Creator. In the first place amongst these there are the Mohammedans, who along with us adore the one and merciful God, who on the last day will judge mankind.
So they are asserting that Mohammedans worship the same god. Professing to hold the Faith of Abraham is one thing. But the "council" did not assert that they "PROFESS" to worship the same God as Catholics, and anybody who is not a complete moron knows right off the bat that Muslims DO NOT profess to worship the same God as Catholics.
One could simply split such a statement into many smaller sentences, which together express each idea expressed in the larger sentence that has more commas.
But the plan of salvation also includes those who acknowledge the Creator. In the first place amongst these there are the Mohammedans. The Mohammedans profess to hold the faith of Abraham. Along with us adore the one and merciful God, who on the last day will judge mankind.
So anyway :plant: