What must be recognized is that the Catholic Church teaches as the Bible reveals that those who reject the Church founded by Jesus Christ reject Christ Himself and thus the truth. Jesus declared to His chosen representatives, "Anyone who rejects you, rejects me" (Lk.10:16). And it is a dogma of the Catholic Church that she is the one true Church founded by Jesus Christ:
Pope Innocent III (1198-1216) solemnly declared in the Profession of Faith for the Waldensians (1208):
By the heart we believe and by the mouth we confess the one true Church, not of heretics, but the Holy Roman Catholic, and Apostolic Church outside which we believe no one is saved.
At the 14th Ecumenical Council, Lyons II (1274), it was solemnly declared in its Profession of Faith:
The most holy Roman Church... firmly holds, preaches, declares, and teaches;... that the true Church is holy, Catholic, apostolic, and one... Also this same Roman Church holds the highest and complete primacy and spiritual power over the universal Catholic Church.
Pope Pius IX (1846-78) declared in Singulari Quidem (1856):
The Church is One, Holy, Catholic, Apostolic, and Roman: unique, the Chair founded on Peter ... Outside her fold is to be found neither the true faith nor eternal salvation, for it is impossible to have God for a Father if one has not the Church for a Mother.
At Vatican Council II none of this historic teaching was changed or modified as many think. For example, in the Decree on the Catholic Eastern Churches (no. 2) it was declared:
The holy Catholic Church, which is the Mystical Body of Christ, is made up of the faithful who are organically united in the Holy Spirit by the same faith, the same sacraments and the same government.
To make it clear that by "Catholic Church" the Council meant the Roman Catholic Church with the successor of Peter, the Pope of Rome, as its visible head, let me quote these from the Constitution On the Church (8 and 23):
This is the only Church of Christ which we profess in the Creed to be one, holy, catholic and apostolic, which our Savior, after his resur- rection, entrusted to Peter's pastoral and shepherding care (cf.Jn.21: 17), commissioning him and the other apostles to extend and to rule it (cf.Mat.18:17-18; 28:18, etc.), and which he raised up for all ages as "the pillar and foundation of the truth" (1 Tim.3:15). This Church, established and organized as a society present in this world, subsists in the Catholic Church, which is governed by the successor of Peter (i.e., the Pope) and the Bishops in communion with him.
The Roman Pontiff, as the successor of Peter, is the perpetual and visible source and foundation of the unity both of the bishops and of the whole company of the faithful. The individual bishops are the visible source and foundation of unity in their own particular churches (i.e. dioceses), ... it is in these and formed out of them that the one and unique Catholic Church exists.
Thus, at Vatican II the Catholic Church still made it clear that she is the one Church established by Christ.
Evangelicals (and all Protestants), by definition, reject the teachings and authority of the Catholic Church. Thus, in effect, they reject Christ. Though the sound arguments of this booklet should be enough to those who are open to truth, the following authoritative Church statements should make it quite clear that Catholics and Evangelicals (and all Protestants for that matter) have no real grounds for cooperation.
Pope Boniface I (418-22) declared in his letter to the Thessalonians that "whosoever has cut himself off from the Church of Rome has become alien to Christianity."
Pope Leo XIII (1878-1903) declared in Satis Cognitum (On the Unity of the Church, 1896):
Remember and understand well that where Peter is, there is the Church; that those who refuse to associate in communion with the Chair of Peter belong to Anti-Christ, not to Christ. He who would separate himself from the Roman Pontiff has no further bond with Christ.
In his Apostolic Letter, Quotiescumque Nobis (1961) Pope John XXIII (1958-62) gives us the logical sequence for those who would be joined to Christ:
It is impossible to be joined to God except through Jesus Christ; it is impossible to be united to Christ except in and through the Church, which is His Mystical Body; finally, it is impossible to belong to the Church except through the bishops, who are the successors of the Apostles and united to the Supreme Pastor, the successor of Peter.
Pope Paul VI (1962-78) declared in Evangelii Nuntiandi (On Evangelization in the World, 1975):
It happens that not without sorrow we hear people... continually claiming to love Christ but without the Church; to listen to Christ, but not to the Church; to belong to Christ; but outside the Church. The absurdity of this is clearly evident in this phrase of the Gospel: "Anyone who rejects you, rejects me" (Lk.10:16).
There are many who think Pope John Paul II has never taught what has been presented so far. But this is not so. In his address to the theologians of Spain (December 20, 1982), the Holy Father made it clear that:
One cannot believe in Christ without believing in the Church, the Body of Christ... Faithfulness to Christ, therefore, implies faithfulness to the Church.
The teaching of the Church is clear: those who do not belong to the Catholic Church, nor hold the Catholic Faith, do NOT belong to Christ, Whose Body is the Catholic Church. Any relations with Protestants, then, must be that of evangelzation, of giving witness to the Catholic Faith, and not that of mere cooperation. Pope Pius XI (1922-39) made this clear in Mortalium Animos (On Fostering True Christian Unity, 1928), when he declared that Christian unity:
can arise only from one teaching authority, one law of belief, and one Faith of Christians... There is only one way in which the unity of Christians may be fostered, and that is by furthering the return to the one true Church of Christ for those who are separated from her; for far from that one true Church they have in the past fallen away...
In his encyclical Ut Unum Sint, Pope John Paul II stated numerous times that for there to be authentic Christian unity, those not in communion with the Catholic Church must come into full unity with her who alone holds the fullness of truth:
Ecumenism is directed precisely to making the partial communion existing between Christians grow toward full communion in truth and charity. (# 14)
The unity willed by God can be attained only by the adherence of all to the content of revealed faith in its entirety. In matters of faith compromise is in contradiction with God who is Truth. (# 18)
Full unity will come about when all share in the fullness of the means of salvation entrusted by Christ to his Church. (# 86)
The Catholic Church, both in her praxis and in her solemn documents, holds that communion of the particular Churches with the Church of Rome, and of their Bishops with the Bishop of Rome, is - in God's plan- an essential requisite of full and visible communion. (# 97)
The Pope, then, admits that the only way for Christians to be united with the unity willed by God is "by the adherence of all to the content of revealed faith in its entirety." Revealed faith in its entirety exists only in the Catholic Church. This means that all non-Catholics who profess belief in Jesus Christ must, for example, accept and believe the divinely revealed truths of: Papal infallibility, the Marian dogmas, Purgatory, the Sacrifice of the Mass, the Real Presence, the seven Sacraments, etc. In other words, they must convert to Catholicism and become members of the Catholic Church. Otherwise, they exist in opposition to God's will.
Of course, unity is not an end in and of itself. The purpose of working for Christian unity is to bring those outside of the one true fold into it that they might be saved. Thus, ultimately, what is at stake here is the salvation of souls.
With the most solemn and highest exercise of Church authority, Pope Eugene IV (1431-47), in the Bull Cantata Domino at the Council of Florence in 1441, defined and declared ex Cathedra, and thus infallibly, that:
[The Holy Roman Church] firmly believes, professes and teaches that none of those who are not within the Catholic Church, not only Pagans, but Jews, heretics and schismatics, can ever be partakers of eternal life, but are to go into the eternal fire 'prepared for the devil and his angels" (Mat.25:41), unless before the close of there lives they shall have entered into that Church; also that the unity of the Ecclesiastical body is such that the Church's Sacraments avail only those abiding in that Church... moreover, that no one, no matter what alms he may have given, not even if he were to shed his blood for Christ's sake, can he be saved unless he abide in the bosom and unity of the Catholic Church.
Of course, no one can enter into and "abide in the bosom and unity of the Catholic Church" unless (presuming they have been validly baptized) they hold in its entirety the Catholic Faith. This is why Pope Pius IX infallibly declared that "to believe that good hope at least is to be entertained of the eternal salvation of all those who are not at all in the true Church of Christ" is to be "absolutely rejected and condemned by all the sons of the Catholic Church" (Syllabus of Errors, 17).
Nevertheless, the above facts and this defined dogma are ignored, if not denied, by those "Catholics" who cooperate with and seek unity with those non-Catholics who profess belief in Jesus Christ as Lord and Savior, for the latter by definition reject dogmas of the Church. In doing so, the former are misleading both themselves and those with whom they cooperate, for there can be no real cooperation, let alone unity, when truth is either ignored or rejected -by either party.
It must, again, be recognized that those who ignore or reject divine truth, ignore or reject God Himself who is truth. This is what we will look at next.