Of course Protestants are heretics. What is a heretic? A heretic is someone who denies a truth revealed by God. Protestants deny almost all of them. They deny the true presence, purgatory, the sacrificial nature of the Mass, the preisthood, the Papacy, the complete canon of the Bible, the Assumption, the Immaculate Conception, five of the seven sacraments, etc. etc. etc. It only takes the denial of one dogma to make a person a heretic - the Protestants deny the majority of the dogmas.
Of all the heresies in the history of Christianity, the modern day Protestants are about as bad as it gets. They have almost no resemblance to Biblical or historical Christianity. Most of them have maintained belief in the inspiration of the Bible, the Divinity of Jesus, and the Trinity (although more and more are now denying that), but aside from these truths they have rejected almost all the rest. Of course they are Protestants… and don’t forget every single heretis without exception will indeed go to hell, as has been defined de fide by the Church.
Pope Eugene IV, Council of Florence, “Cantate Domino,” 1441, ex cathedra:
“The Holy Roman Church firmly believes, professes and preaches that all those who are outside the Catholic Church, not only pagans but also Jews or heretics and schismatics, cannot share in eternal life and will go into the everlasting fire which was prepared for the devil and his angels, unless they are joined to the Church before the end of their lives; that the unity of this ecclesiastical body is of such importance that only for those who abide in it do the Church’s sacraments contribute to salvation and do fasts, almsgiving and other works of piety and practices of the Christian militia productive of eternal rewards; and that nobody can be saved, no matter how much he has given away in alms and even if he has shed blood in the name of Christ, unless he has persevered in the bosom and unity of the Catholic Church.”
Don’t let the indifferent liberals try to convince you otherwise. The above quote is an infallible dogma of the faith. The liberals always try to “explain away” that quote and the others like it, but it is true nevertheless and all Catholic are bound to believe it. I’ll end with a quote written by a Pope in order to counter the error of indifferentism (which is everywhere today) when it was first being born…
Pope Gregory XVI, Summo Iugiter Studio, May 27, 1832, on no salvation outside the Church: “Finally some of these misguided people attempt to persuade themselves and others that men are not saved only in the Catholic religion, but that even heretics may attain eternal life… You know how zealously Our predecessors taught that article of faith which these dare to deny, namely the necessity of the Catholic faith and of unity for salvation… Omitting other appropriate passages which are almost numberless in the writings of the Fathers, We shall praise St. Gregory the Great who expressly testifies that THIS IS INDEED THE TEACHING OF THE CATHOLIC CHURCH. He says: ‘The holy universal Church teaches that it is not possible to worship God truly except in her and asserts that all who are outside of her will not be saved.’ Official acts of the Church proclaim the same dogma. Thus, in the decree on faith which Innocent III published with the synod of Lateran IV, these things are written: ‘There is one universal Church of all the faithful outside of which no one is saved.’ Finally the same dogma is also expressly mentioned in the profession of faith proposed by the Apostolic See, not only that which all Latin churches use, but also that which… other Eastern Catholics use. We did not mention these selected testimonies because We thought you were ignorant of that article of faith and in need of Our instruction. Far be it from Us to have such an absurd and insulting suspicion about you. But We are so concerned about this serious and well known dogma, which has been attacked with such remarkable audacity, that We could not restrain Our pen from reinforcing this truth with many testimonies.”