The Reformed tend to be very emotionally-charged about subjects, whether Rome or something else. They have kept a lot of the bitterness of the Huguenots, Dutch, Genevan Calvinists, and the English Puritans, all of whom considered themselves to be “Reformed” Catholic Christians, the “abuses” of the middle ages thrown out.
This theology is principally identified not by a hatred of Rome (that’s more of a secondary characteristic), but by the adjective TULIP:
Total depravity: all human beings are totally depraved in every faculty, will, and natural ability. We are thus unable to come to God of our own power, or to do truly good, holy works of our own power. “Total” depravity, I have heard some Reformed people say, does not indicate that we are all as completely evil as we can possibly be, but rather that the totality of our human nature is depraved or fallen: every part of our body, heart, soul, mind, and strength.
Unconditional Election: all human beings who are to be saved are elected to be saved by God before the beginning of creation; consequently, all human beings who are to be damned are elected to be damned by God before the beginning of creation. This is usually argued as a natural consequence of God’s total sovereignty over time, space, and existence itself. This naturally puts our free will in question.
Limited Atonement: Christ the Lord died in a limited way, for those He had elected to be saved only. His Atonement is not considered to have been unlimited, for every sinner in the world, as the Orthodox, Roman Catholics and Arminian (free-will-believing Protestants) say.
Irresistible Grace: The idea that God’s divine holy unmerited grace is so strong that it automatically converts everyone it is applied to (i.e. the elect). We cannot say no to it, nor can we say “yes” to merit it.
Perseverance of the Saints: Often called “Once Saved Always Saved”, the doctrine that everyone who truly has faith cannot possibly be lost or fall away into infidelity again. Based on John 10’s good shepherd allegory, about Christ’s sheep always hearing His voice, and He gathering them to Himself infallibly.
These are the main statutes of the “Calvinist”, “Reformed”, “Presbyterian”, or “Radical Reformation” movement.