Apotheoun: would you mind answering the above question?
I have been offline for a few days, so I apologize if I missed your response.
The only act of worship acceptable to the Father is the oblation of the Son of God made man, which is rendered present through the divine liturgy, or what Western Catholics call the Mass.
Do Presbyterians offer the one oblation of Christ in the Eucharist? No.
Do Presbyterians offer divine worship to God the Father through the Son in the power of the Spirit? No.
Do Presbyterians have a defective faith in Christ? Yes, but so did the Arian heretics, and the Church excluded them from her ranks. The Arians did not worship Christ because they did not believe in Him in an Orthodox manner. I would say that Presbyterians are - like the Arians - heretics, albeit most are material heretics as opposed to formal heretics, but they are heretics nonetheless. I too was once a Protestant heretic, but I left that heresy behind more than twenty years ago, and I did so because I knew that I could not worship and serve God truly as a Protestant.
Now, all of this is really quite beside the point, unless you are trying to argue that Muhammadans are like Protestants. Is that what you are arguing? Are you seriously trying to posit the odd notion that a non-Christian religion (i.e., a form of pagan fatalism) like Islam is somehow related to the Church, and that a false prophet brought a variety of the true faith to the Arab world? To me such an argument is utter nonsense, but if that is what you believe I cannot stop you from affirming it. Such a position is contrary to scripture and tradition, but you have free will and can abuse that freedom in whatever way you wish.
Postscript: To be fair to you I suppose that your question was not meant to imply a connection between Protestantism, a recent Western heresy from an Eastern Christian perspective, and the false religion of Muhammad.