In the Gospels, Jesus spoke of "sheep not of this fold." In our times there has been a pernicious error arise that Jesus was speaking of the Mormons with this line. As a result of this error, it's essential that we understand what Jesus was saying when He spoke of "sheep not of this fold."
As the Scriptures state:
I am the good shepherd; and I know mine, and mine know me. As the Father knoweth me, and I know the Father: and I lay down my life for my sheep. And other sheep I have, that are not of this fold: them also I must bring, and they shall hear my voice, and there shall be one fold and one shepherd. Therefore doth the Father love me: because I lay down my life, that I may take it again. No man taketh it away from me: but I lay it down of myself, and I have power to lay it down: and I have power to take it up again. This commandment have I received of my Father. (John 10:14-18)Before we can understand any passage of Scripture we have to put it in context. To start, who was Jesus speaking to? He certainly was speaking to the Jews. In particular, He was speaking to the Pharisees when He spoke of Himself as the Good Shepherd. And at this time the Jews did not understand or even fathom that salvation was possible for non-Jews. These non-Jews, the Gentiles, would be saved by Christ's Sacrifice on the Cross. And in this way, the Good Shepherd would draw all men to Himself - the Jews (those of the fold) and the Gentiles (the sheep not of this fold). And together they would form one sheepfold with Christ as the One Shepherd.
Unfortunately, the Mormons have twisted Scripture around and sought to apply words spoken by Jesus thousands of years before their founding to them. The Mormons emphasize that Jesus was calling them to be of a different sheepfold. But this is also wrong. The emphasis of Jesus in the passage is not that there are different groups of followers of His; rather, the Lord was making clear that He would bring all peoples together into one sheepfold. It is only in that one sheepfold (the Church) that we can all come together and truly follow the Lord.
The Staff of Catholic Answers explains:
Most Catholic biblical scholars, following the teaching of the early Church Fathers, agree that the "other sheep" are the Gentiles, to whom the gospel was sent after the Jews rejected Christ (Rom 11:11-12).
During his public ministry Jesus confined his proclamation of the gospel to the Jews (Mt 10:5-6, 15:24), and initially this remained the focus of the apostles' preaching, although Jesus had foretold that the gospel would eventually be carried to "all nations" (Mt 28:19, Acts 1:8). This opening up of God's blessing even to Gentiles was foretold in the Old Testament (Ps 2:7; Is 2:2-6).
Paul explained this to Gentile Christians:
"Therefore remember that at one time you Gentiles in the flesh, called the uncircumcision by what is called the circumcision, which is made in the flesh by hands--remember that you were at that time separated from Christ, alienated from the commonwealth of Israel, and strangers to the covenants of promise, having no hope and without God in the world. But now in Christ Jesus you who once were far off have been brought near in the blood of Christ." (Eph 2:11-13; cf. Rom 3:22; Gal 3:27-28)Another member of Catholic Answers further states:
In reality, the "other sheep" Jesus mentions are the righteous Gentiles, who did not belong to the "fold" of God’s chosen people, Israel, but who would respond to the gospel when preached to them. While Christ’s earthly ministry served the Jewish people almost exclusively, his great commission to the apostles before his ascension sent them into all the world to preach, baptize and thus unite his believers in one fold (Mt 27:19). Because "he that heareth you heareth me" (Lk 10:16), to hear the gospel from the lips of his disciples is to hear Jesus himself
The understanding of the "other sheep" as the Gentiles who would come to believe in Christ is the natural understanding of the passage. Mormons sometimes ask Christians, "If the ‘other sheep’ weren’t in the New World then who were they?"
A Christian often will be perplexed at the fact the question was asked at all and respond, "Well, they’re the Gentile Christians, of course. How could anyone think the text suggests otherwise?" The New Testament has a running theme of how salvation comes from the Jews to the Gentiles. It appears across multiple books, in all of the gospels and most of the epistles. Jesus’ statement about gathering other sheep in the future is simply one more instance of the gospels dealing with this theme.
The fact that Mormons often do not spot the obvious, face-value interpretation of the text reveals how little Mormons have been exposed to the historic understanding of the passage and how little they have been encouraged to think through its rationale. They have not tried to understand the New Testament as a whole, integrating and understanding its individual passages with other passages and with the general historical backdrop. Instead, they have had the interpretations of certain alleged proof texts force-fed to them in a way that keeps them from knowing of the existence of other, more plausible interpretations.
Above all, the sheep "not of this fold" are the Gentiles. Together with the original Jews who accepted Christ, the Church was to include all men. This false teaching of the Mormons has distorted the understanding of Christ's beautiful role as the Good Shepherd. Like other cults (Jehovah's Witnesses, Christian Scientists), the writings of the Mormons are to be burned and condemned. And like these groups, the Mormons do not accept the Trinity and therefore are not Christians at all; rather, they are a pernicious form of paganism.