That term alter Christus is being distorted beyond all recognition. The Catholic Church does not teach that each priest is some fresh new Messiah.
...or people who mistakenly think there is a "co-redeemer."
That term too is being distorted, and is not even a teaching of the Catholic Church.
The same falsehoods about Catholicism are repeated here over and over, as a fetish, regardless how many times they are corrected. What can the motive be?
It is because they don't really know our God. We really have to pray for all those who haven't known God's true love. It is kind of sad. There but for the grace of God, go us.
It is biblical prophecy:
John Chapter 15: 17-21
This I command you: love one another.
"If the world hates you, realize that it hated me first. If you belonged to the world, the world would love its own; but because you do not belong to the world, and I have chosen you out of the world, the world hates you. Remember the word I spoke to you, 'No slave is greater than his master.' If they persecuted me, they will also persecute you. If they kept my word, they will also keep yours. And they will do all these things to you on account of my name, because they do not know the one who sent me.
Truth is always the motive.