Who then, you may wonder, are the other sheep that are "not of this fold", yet for whom Christ also gave His life?
Well to explain that let us set the scenario:
It is the time after the great tribulation spoken of by Christ in Matthew 24:21, when Christ is returning to establish the Kingdom of God on Earth. 1 Thes 4:16-17 states:
"For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first: Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord."
Also, 1 Corin. 15:51-52 states: "Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed, in a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed."
Those verses clearly indicate that all true christians will be changed into immortal spirit beings at the return of Christ, while He is yet in the air on His way down to this earth and will go to be with Him where He is, in His headquarters (on the Earth) forever.
Now read carefully Matt. 25:31: "When the Son of man shall come in his glory, and all the holy angels with him, then shall he sit upon the throne of his glory: And before him shall be gathered all nations: and he shall separate them one from another, as a shepherd divides his sheep from the goats:
And he shall set the sheep on his right hand, but the goats on the left. Then shall the King say to them on his right hand, Come, you blessed of my Father, inherit the kingdom prepared for you from the foundation of the world: For I was hungry, and you gave me meat: I was thirsty, and you gave me drink: I was a stranger, and you took me in: Naked, and you clothed me: I was sick, and you visited me: I was in prison, and you came to me.
Then shall the righteous answer him, saying, Lord, when did we see you hungry, and fed you? or thirsty, and gave you drink? When did we see you a stranger, and took you in? or naked, and clothed you? Or when did we see you sick, or in prison, and came to you? And the King shall answer and say to them, truly I tell you, inasmuch as you have done it to one of the least of these my brethren, (pointing to those who have already been changed and are now with Him), you have done it to me.
Then shall He say also to them on the left hand, Depart from me, you cursed, into everlasting fire, prepared for the devil and his angels: For I was hungry, and you gave me no meat: I was thirsty, and you gave me no drink: I was a stranger, and you did not take me in: naked, and you did not clothe me: sick, and in prison, and you did not visit me.
Then shall they also answer him, saying, Lord, when did we see you hungry, or thirsty, or a stranger, or naked, or sick, or in prison, and was not kind to you? Then shall he answer them, saying, truly I tell you, inasmuch as you did not do it to one of the least of these, (pointing to those with Him who have already received immortal life), you did not do it to me. And these shall go away into everlasting punishment: but the righteous into life eternal."
So then, it is clear that those who do good or evil to any true christians in this life are virtually doing such to Jesus Christ, and will be rewarded accordingly at the return of Christ. Many of those individuals may have never attended a church in their lives! Yet they are the other sheep spoken of in Matthew 25:33, "And He shall set the sheep on his right hand, but the goats on the left."
Naturally christians should also visit the sick and prisoners, and give to the poor as they are able, but they are not the sheep spoken of in Matthew 25:33, for as the scriptures reveal, by that time they would have already been transformed into immortal spirit beings, newly born members of the family of God.