You may ask, "Couldn't one claim that, though much of their theology is wrong, it does not mean that Protestants are separated from Christ and actually believe in a different God?" No, this could not be true. Some fundamental theology will help us to see why.
To believe in God is to believe in who He is. This should be self-evident. "Hear O Israel, the Lord is our God, the Lord is one" (Deut.6:4). God's unity, or "oneness," means that He is indivisible. God's oneness includes all His divine attributes; for God is Eternal, Everywhere Present, All-mighty, All-knowing, All-wise, Holy, Just, Good (this includes loving), Merciful, True, Faithful, and Unchangeable.
Because God is infinite, His attributes are infinite. We must recognize that there is no distinction between God's attributes and Himself. As God is one and indivisible, so His attributes are one and indivisible. Since our minds are finite we must think of God's attributes as distinct, if we are to think of them at all. Nevertheless, as God is one and indivisible, so His attributes are one and indivisible. Thus, the attributes of God are not distinct from His very Self, and in God neither are they distinct from one another.
This means that not to believe in just one of these attributes is to not believe in God at all. God cannot be God if He did not have only one of these attributes; nor could God be God even if He lacked absolute perfection in only one attribute. God, by definition, can NEVER lack even absolute perfection in any of these attributes.
This is all fundamental theology, the foundation upon which everything else pertaining to God, and thus to Christ and Christianity, is built. We will now look at one of God's attributes in relation to ecumenism. This attribute will be truth.
The Attribute of Truth
Since God is true, it necessarily follows that God reveals only Truth; God speaks only Truth; God acts only in Truth; God can only be known in truth; God demands belief in and conformity to Truth. Now, since God is also one, and thus, indivisible (i.e. God has no parts), the same must be said concerning the attribute of Truth. Truth, divine Truth, MUST be one and indivisible if it is an attribute of God. As it is an attribute of God, Who has no parts, so there is no division or parts in Truth. As a result of this, the following must be held and affirmed:
Since Truth cannot be divided, to deny, or to fail to believe in just ONE divinely revealed truth (i.e. a dogma of the Church) is to fail to believe ENTIRELY what God has revealed. Again, as an attribute of God, Truth has NO parts. It can only be believed in its entirety or it is not held at all, for Truth cannot be divided. Think about this...
Jesus, the Second Person of the Blessed Trinity, identified Himself with the Truth and as the Truth (Jn.14:6), and as belief in and submission to Christ is necessary for salvation, so, then, is belief in Truth necessary for salvation. The very nature of God demands belief in and conformity to truth, if one is to be saved. Again, since Truth is indivisible it must be believed in its entirety. As a result of this, the following position and conclusion is unavoidable:
We must of necessity conclude that one who fails to believe in just one particular divine truth, that is, one who rejects just one dogma of the Catholic Church, cannot in reality believe in the God of the Bible, the God of the Catholic Church. By definition, this person cannot be united to Christ Who is Truth Incarnate. Thus, this person cannot be saved.
Since all Protestants, let alone all other non-Catholics, reject what the Catholic Church teaches as truths revealed by God (i.e., Papal infallibility, the Marian dogmas, Purgatory, the Sacrifice of the Mass, the Real Presence, etc.), we must of necessity conclude that in rejecting just one particular divine truth, that is, in failing to believe in just one dogma of the Church, these persons are rejecting God. Remember, there is no distinction between God and His attributes. Thus Protestants, as they are, cannot be saved.
It is either that, or one the following MUST be held:
1) Truth, and our belief in it, does not really matter for salvation. IF this were true, THEN, Jesus does not matter for salvation since He equated Himself with the Truth and identified Himself as the Truth (see Jn.14:6). Of course, no real Christian can hold this, OR:
2) Truth is divisible, which means it does not need to be completely accepted and embraced, for some "parts" of Truth can be held while at the same time others can be rejected. IF this were true, THEN Truth can not be an attribute of God because God is one and indivisible and His attributes are identical with Him. But this would mean that God is NOT true. IF God were not true, THEN God is not perfect. IF this were true, THEN there is no God, for God is, by definition, infinitely perfect and true. Thus, to hold this option makes one an atheist.
What do these undeniable facts reveal? First, these facts reveal that Catholics and Protestants cannot truly join in prayer together at ecumenical gatherings, for the "God" of Protestants (and thus Evangelicals) is not the one true God, indivisible in all of His attributes. Catholics and Protestants may profess to believe in the same God, in the same Jesus, etc., but that to which we attribute to God in both His nature and works are contradictory and irreconcilable. Second, these facts reveal the need, again, not for mere cooperation or ecumenical prayer services, but evangelization.
To hold and believe that a person can still be united to Christ and be saved without having to believe those truths which God has revealed for our salvation, which is what the dogmas of the Faith are, one is holding either #1 or #2 (or both). There are no other options. To hold #1 makes one a non-Christian. To hold #2 makes one a complete atheist. Neither of which can be saved. The only other choice is to believe the absolute necessity of holding in its entirety the One True Faith revealed by God and given to us by Christ -the Catholic Faith. This is what the Catholic Church has always formally taught:
In the ancient Athanasian Creed, composed sometime before the year 400 A.D., it is declared:
Whoever wishes to be saved needs above all to hold the Catholic faith; unless each one preserves this whole and inviolate, he will without a doubt perish in eternity... This is the Catholic faith; unless each one believes this faithfully and firmly, he cannot be saved.
Pope Eugene IV (1431-1437) solemnly declared in his Bull Exultate Deo (1439):
Whoever wishes to be saved needs, above everything else, to hold the Catholic faith. Unless one preserves this faith whole and inviolate he will perish in eternity, without a doubt.
At Vatican Council I, in the Dogmatic Constitution On Faith (chap.3), it was solemnly declared:
Since without faith it is impossible to please God, no one may be justified without it, nor will anyone attain eternal life unless he perseveres to the end in it... all those things are to be believed by divine and Catholic faith which are contained in the written Word of God or in Tradition, and which are proposed by the Church either in solemn judgment or in its ordinary and universal teaching office as divinely revealed truths which must be believed.
In the Dogmatic Constitution on the Church of Christ (ch.3) it was solemnly declared:
We teach and declare that the Roman Church, by the disposition of the Lord, holds the sovereignty of ordinary power over all others... When, therefore, this bond of unity with the Roman Pontiff is guarded, both in government and in profession of the same faith, the Church of Christ is one flock under one supreme shepherd. This is the doctrine of Catholic truth from which no one can deviate without losing his faith and salvation.
Pope Benedict XV (1914-1922), in his first Encyclical Ad beatissimi (1914), repeated this same principle:
The nature of the Catholic faith is such that nothing can be added, nothing taken away. Either it is held in its entirety or it is rejected totally. This is the Catholic faith which, unless a man believes faith- fully and firmly, he cannot be saved.
May all who claim to be Catholic recognize the true teachings of Mother
Church on the necessity of holding the Catholic Faith in its entirety for
salvation. May all Protestants who honestly seek Christian unity in response
to the prayer of our Lord Jesus in John 17, recognize that, 1) this is
the true teaching of the Catholic Church, and 2) this teaching is revealed
from God, from which the Catholic Church can never deviate.