What is the purpose of God's elect people? Our purpose is to do the will of God. Our purpose is to keep His commandments and to obey His Word. That's our purpose.
Some would say, "Oh, but I must know exactly why I do things. I must know exactly why God commands me to feed sheep before I actually go and do it."
Really? Did Abraham understand the purpose behind God's commanding him to take his only son Isaac and offer him as a sacrifice?
No, he had no idea of God's purpose for it. Even before that, did Abraham know why God commanded him to leave Ur of the Chaldees and go sojourn in the land of Canaan? Not according to this Scripture:
Hebrews 11:8 By faith Abraham, when he was called to go out into a place which he should after receive for an inheritance, obeyed; and he went out, not knowing whither he went.
Or, did the prophet Isaiah understand the purpose of God when the Lord commanded him to walk naked and barefoot for three years?
Isaiah 20:2 At the same time spake the LORD by Isaiah the son of Amoz, saying, Go and loose the sackcloth from off thy loins, and put off thy shoe from thy foot. And he did so, walking naked and barefoot.
3 And the LORD said, Like as my servant Isaiah hath walked naked and barefoot three years for a sign and wonder upon Egypt and upon Ethiopia;
Probably not. Or even if he did he certainly could have questioned the reasoning behind it. "Lord, you want me to walk naked and barefoot for three whole years—just so you can use me as a sign of some kind to Egypt and Ethiopia?"
Christians today, even God's elect, have gotten into their minds that they must understand and approve of God's commandments to them before acting upon them. Of course we want to check things out and search the Scriptures to make sure it is so. But there's nothing in the Bible that indicates God is waiting for us to give our consent or approval towards His directives for us.
Some make it appear as though the Lord has submitted His commandment to us in order for us to approve/disapprove. "Well, I don't know about this particular command, Lord. I understood and agreed with the command to go out into the world to bring a gospel that could save people; but this idea of feeding sheep, well, I'm sorry, but it simply does not meet with my approval. So I won't be carrying it out if that's alright with you." Ridiculous. Foolishness. God is not asking us for our approval. He's God. He's commanding us. "Feed My sheep" is NOT a request. It's a command. Understand it or not. The command has been given.
Did Ezekiel understand the purpose behind this command:
Ezekiel 4:4 Lie thou also upon thy left side, and lay the iniquity of the house of Israel upon it: according to the number of the days that thou shalt lie upon it thou shalt bear their iniquity.
5 For I have laid upon thee the years of their iniquity, according to the number of the days, three hundred and ninety days: so shalt thou bear the iniquity of the house of Israel.
6 And when thou hast accomplished them, lie again on thy right side, and thou shalt bear the iniquity of the house of Judah forty days: I have appointed thee each day for a year.
Maybe he had some slight understanding of it, maybe not. But he did it. Whether we understand the full meaning and purpose behind a command or not, we're called upon to obey it.
And one of the major reasons why God has given this command is to try (test) His people in the Day of Judgment. What's the test? The test is to see if we truly love Christ or not. And does the Bible define love for Christ? "If you love Me, keep My commandments." Not just commandments you agree with and approve of, but commandments you may not fully understand or even approve of. Three times Jesus asked Peter, “Lovest thou Me?” Once again, in the Bible love is an action word. If Peter loved Christ he would respond obediently to the command given him to feed the sheep. Peter is a picture of God’s elect children in our present day. How we respond to the command to feed sheep at this time will determine the answer to the question: “lovest thou Me?”