Before we proceed it must be made clear that the differences between Catholics and Evangelicals are not mere differences in degree of Christian truth/doctrine, but differences in kind. We are talking about a qualitative difference. Between Catholics and Evangelicals (this also includes all Protestants), it is a matter of mutually exclusive and irreconcilable beliefs,of opposite beliefs.

   Let me put before you some concrete examples:
   The Jesus in Whom Catholics believe, profess, obey, and worship was born of a woman who was:

    A) immaculately conceived
    B) sinless throughout her life
    C) a perpetual virgin
    D) assumed body and soul into Heaven

   These are all dogmas of the Catholic Faith. Dogmas are truths formally revealed by God and proposed by the Church as necessary for belief, and thus, belief in them is necessary for salvation.

    Now, the Jesus in whom Evangelicals (and all Protestants for that matter) profess belief in and worship was born of a woman who was: NOT-A, NOT-B, NOT-C, and NOT-D. Thus, this is not a matter of differences by degrees. This is a different Jesus! This is a rejection of divinely revealed truth. It is an opposite of what Catholics hold and believe.

    But wait a minute! These are not fundamental truths, are they? It is true, they are not the foundation upon which the Christian Faith rests. Even the Catholic Church holds that these Marian doctrines are not at the top of the "hierarchy of truths." But that does not mean that a rejection of these is NOT a rejection of basics. I will demonstrate how the rejection of even these Marian dogmas is in reality a rejection of God Himself - and you can't get any more basic than this.

    Our existence on earth is ultimately to get to Heaven, to be united with God. The Catholic Church has always taught that we were created to know God, to love Him, and to serve Him in this world, and to be happy with Him forever in Heaven. Since attaining Heaven is the very purpose for our existence here on earth, God would not "waste His time," nor our short time, by revealing things which were not be beneficial for our salvation. God does not reveal divine truths to help us win at "Trivial Pursuit," or merely get college degrees, or so we could win on "Jeopardy." No, God's very purpose for revealing His truths is so that we could be made free from sin and its consequences, -eternal death (Jn.8:32). Therefore, IF God formally reveals a truth, which the Catholic Church calls a dogma, THEN our belief in it is necessary for our salvation.

    IF God has revealed a truth, THEN not to believe in it, to deny that truth revealed by God is to deny the very authority of God Who revealed it. This is true no matter what that truth is which God has revealed. To deny the authority of God is nothing other than a denial of God Himself, and NO ONE can be saved who denies God. If God has revealed it, then ALL men must believe it. IF God has revealed the above doctrines concerning the very Mother of Jesus Christ, THEN Protestants, (all men, in fact) MUST believe them. Since these doctrines are divinely revealed truths, to deny them is ultimately to deny God Who revealed them.
 

   The issue, then, is not whether the Marian doctrines are basic or foundational to the Christian Faith; it is not whether these doctrines have any direct bearing upon how we are saved, but rather, the issue concerns the very authority of God. And nothing can be more basic to the Christian Faith than the very authority of God. Catholics and Evangelicals, then, disagree on the very authority of God.

   Any supposed "agreements" between Evangelicals and Catholics on even just essentials, while each side professes to maintain faithfulness to their respective traditions, is impossible. By analogy, different fruit (i.e., doctrines) can not come from the same "essential" tree. And what Evangelicals believe and hold (which is not at all uniform) is the opposite from what the Catholic Church believes and teaches.

   To make it abstract, in the doctrines which follow, the Jesus in Whom Catholics believe in did A, B, C, D and continues to do E, and His work on the Cross does F (as revealed in Sacred Scripture). The Jesus in whom Evangelicals believe in did NOT-A, NOT-B, NOT-C, NOT-D,does NOT-E, and His death on the Cross does NOT-F. These examples will make it clear that we hold mutually exclusive doctrines, and thus disagree not only one the one Faith revealed by God, but we disagree on the one Lord Himself.

   A) The Jesus in Whom Catholics believe in, profess, obey, and worship established a visible Church with a visible authority and the hierarchical structure of a kingdom and a body (see Acts 6: 6; 14:23; 1 Cor.12:28; 1 Tim.4:14;Titus 1:5); whose bishops continue to exercise the same teaching and governing authority of the Apostles (see Acts 20:28; 1 Tim.5:21-22; 2 Tim.2:2; 4:2-5; Titus 2:15). The Jesus in whom Evangelicals believe in and worship did NOT establish such a church.

   B) The Jesus in Whom Catholics believe in... and worship established the Papacy by building His Church upon St. Peter, thereby giving the world a visible teaching and governing authority representing Christ's own teaching and governing authority (Mat.16: 18-19; Lk.22:31-32; Jn.21:15-17). The Jesus in whom Evangelicals believe in did NOT establish such an authority.

   C) The Jesus in Whom Catholics believe in... and worship established a visible,sacerdotal priesthood to consecrate bread and wine into His Sacred Body and Blood, to perpetuate His one sacrifice of the cross, and to apply its fruits and graces down through time to believers, which includes the forgiving of sins (Lk.22:19; Jn.20:21-23; 2 Cor.5:18). The Jesus in whom Evangelicals believe in did not establish such an office or function.

   D) The Jesus in Whom Catholics believe in... and worship established at the Last Supper the one form of Christian worship for the worship of God to fulfill both the First and the Third Commandments. This is none other than the Holy Sacrifice of the Mass (Mat.26:26ff; Mk.14:22ff; Lk.22:19ff; 1 Cor.11:23). The Jesus in whom Evangelicals believe in did NOT establish such a worship service. (This is why Catholics can not, and do not, fulfill their Sunday obligations if they attended Prot services. In fact Catholics are forbidden to actively participate at non-Catholic services.)

   E) The Jesus in Whom Catholics believe in... and worship makes Himself truly present, Body, Blood, Soul and Divinity, under the outward appearance of bread and wine, in the Holy Eucharist (Lk.22:19-20; Jn.6:52, 54-57; 1 Cor.10:16; 11:27). The Jesus in whom Evangelicals believe in does NOT do such a thing. Yet,since the Holy Eucharist IS literally the Body, Blood, Soul, and Divinity of Christ present on earth, to deny that it is, is to deny Jesus himself. There can be no unity, nor cooperation, with those who deny the Eucharistic Lord since at Vatican II, in the Church's very Decree on Ecumenism (ch.1), it was declared that Christ:

   "instituted the wonderful sacrament of the Eucharist by which the unity of the Church is both signified and brought about."

   As you can see, it is not a matter of Evangelicals (or any Protestant)not merely believing as much as Catholics believe, or of each side just holding different interpretations which need to be worked through in greater detail, rather, it is a matter of Evangelicals believing the very opposite what the Catholic Church teaches. You can never reconcile "A" and "NOT-A." Truth, and thus Divine Faith, can never contradict itself. As GOd has revealed, The preaching of the Apostles is that God is faithful: their preaching was not "It is, and It is not" (see 2 Cor.1:18-19).

   What Protestants hold and what Catholics hold are mutually exclusive doctrines and beliefs. But there is only one Lord and one Faith revealed by the Lord. Therefore, the Protestant faith is not the same faith to a lesser degree than that of the Catholic Faith, nay, it is a different faith. It is a different religion. (This was so obvious to men in the 16th through 18th centuries.)

   This is why Venerable Pope Pius IX (1846-78) declared ex cathedra (and thus infallibly) that it is an error to hold and believe that "Protestantism is nothing else than a different form of the same true Christian religion, in which it is possible to serve God as well as in the Catholic Church"(Syllabus of Errors, Proposition, 18).

   There can be no true ecumenism unless one or the other of these systems of belief abandon its teachings. There can be no cooperation with those who hold the very opposite of Catholic teaching, for truth is the prerequisite for both unity and cooperation. Setting aside differences in order to cooperate with those who reject truths revealed by God leads to the sin and error of indifferentism.