Speaking as a Catholic, of which (Catholicism) this post seems directed against, I have honestly never understood why the passage in Matthew gives Protestants such consternation.
Jesus used the word for "rock" to rename Simon bar Jonah.
Does this mean that Catholics/Catholicism believes that God is no longer a "rock of salvation"? IOW, does it mean that Catholics believe Peter REPLACES God? I can say with reasonable confidence, "of course not".
It's a symbolic description of Peter's role in the new Church Jesus was founding. That doesn't mean that God isn't the Head of the Church, it simply means here, on earth, the earthly, fleshly, visible head is the Pope.
Here's something to consider: There can be, logically speaking, two "rocks", one, the "Rock", being God, "rock steady for all eternity", and the other a "rock" as in a cornerstone for the visible Church here on Earth. Note the Capital and lowercase lettering. Does that make it more palitable? Does that stress enough the Catholic teaching I know to exist?
The Pope is the Vicar (meaning representitive, not substitute for) of Christ here on earth, a "little 'r' rock" if you will. God, is the "Rock", the "Rock of Salvation", an eternal rock Who's Nature is to build on Faith. What better way to build a mighty Church on earth than to confer such authority to a leader, a "rock on the earth", as Peter?
Put another way, IMO, the point of Matt 16:18 is not to "replace" God as "the Rock", but rather to place a "rock", in the form of Peter, a human being, here, on Earth, a foundation upon which the rest of the Church can rely. I think that notion is supported by the plain reading of the passage.
Forget about debating "rocks", and get into the meat of the Word.
But truly the article is not anti-Catholic - if anything, it is pro-Torah.
The point of the research project is that the specially announced Name of God, The Rock, was lost in the Septuagint and Vulgate translations.
So instead of "God is The Rock" being one of His Names, in the Song of Moses and the Torah - the term "rock" has been picked up more as a metaphor for God rather than a Name.
Notably most of the debate on this thread has centered around what "rock" means when applied to Peter. (And sadly, next to nothing about the term used in reference to Abraham.)
Nevertheless, my concern is that the Name of God be understood among all believers, Christian and Jew: God is The Rock. It is in the Song of Moses which will be proclaimed in eternity.