Is God's kingdom vegetarian? When Christ restores peace will he fulfill Isaiah's prophecy? Will humans still kill animals? Will Lions still kill lambs? Will the wolf still hunt the sheep? According to Isaiah and Jesus the strong will protect the weak, and creatures whom the fallen nature of our fallen world made enemies will live in peace.
"There shall come forth a Rod from the stem of Jesse, and a Branch shall grow out of his roots. The Spirit of the LORD shall rest upon Him, the Spirit of wisdom and understanding, the Spirit of counsel and might, the Spirit of knowledge and of the fear of the LORD. His delight is in the fear of the LORD, and He shall not judge by the sight of His eyes, nor decide by the hearing of His ears; but with righteousness He shall judge the poor, and decide with equity for the meek of the earth; He shall strike the earth with the rod of His mouth, and with the breath of His lips He shall slay the wicked. Righteousness shall be the belt of His loins, and faithfulness the belt of His waist. The wolf also shall dwell with the lamb, the leopard shall lie down with the young goat, the calf and the young lion and the fatling together; and a little child shall lead them. The cow and the bear shall graze; their young ones shall lie down together; and the lion shall eat straw like the ox. The nursing child shall play by the cobra's hole, and the weaned child shall put his hand in the viper's den. They shall not hurt nor destroy in all My holy mountain, for the earth shall be full of the knowledge of the LORD as the waters cover the sea. And in that day there shall be a Root of Jesse, who shall stand as a banner to the people; for the Gentiles shall seek Him, and His resting place shall be glorious." (Isaiah 11:1-10)
Two basic flaws are made in this argument: 1) When dealing with prophecy one must be very careful about the symbolic language. It is easy to forget and assign literal meanings to words meant to symbolize ideals. 2) If only a select portion of a prophecy is quoted it is easy to assign its fulfillment to the wrong time frame. So, let's start at the beginning of the prophecy.
Isaiah states that a rod or branch would come from Jesse. This is just a fancy way of saying that in Isaiah's future a descendant of Jesse (David's father) would arise. In Revelation 5:5, Jesus is referred to as the "root of David." It was Jesus who fulfilled this promise. "And when He had removed him, He raised up for them David as king, to whom also He gave testimony and said, 'I have found David the son of Jesse, a man after My own heart, who will do all My will.' From this man's seed, according to the promise, God raised up for Israel a Savior -- Jesus -- after John had first preached, before His coming, the baptism of repentance to all the people of Israel" (Acts 13:22-24).
The Spirit of the Lord would rest upon Him. This was seen fulfilled at Jesus' baptism. "When He had been baptized, Jesus came up immediately from the water; and behold, the heavens were opened to Him, and He saw the Spirit of God descending like a dove and alighting upon Him" (Matthew 3:16). By the way, this same symbol is seen in other Messianic prophecies (Isaiah 42:1; 61:1).
The illustration of predator and prey living together in peace is also a common one in prophecy (Isaiah 65:25; Ezekiel 34:25; Hosea 2:18). Key is that peace would exist in God's Holy Mountain. It harkens back to an earlier prophecy, "Now it shall come to pass in the latter days that the mountain of the LORD'S house shall be established on the top of the mountains, and shall be exalted above the hills; and all nations shall flow to it. Many people shall come and say, "Come, and let us go up to the mountain of the LORD, to the house of the God of Jacob; He will teach us His ways, and we shall walk in His paths." For out of Zion shall go forth the law, and the word of the LORD from Jerusalem. He shall judge between the nations, and rebuke many people; they shall beat their swords into plowshares, and their spears into pruning hooks; nation shall not lift up sword against nation, neither shall they learn war anymore. O house of Jacob, come and let us walk In the light of the LORD" (Isaiah 2:2-5). Again in this earlier prophecy was seen the same concepts being represented. Judgment is rendered and peace will follow.
We don't have to guess when these things will take place because the New Testament tells us. The good news, the Gospel, went forth from Jerusalem (Luke 24:47; Acts 1:8). From there it spread to the whole world (Acts 8:4; 13:46-48). And church that was thereby established, God's kingdom, pulled in people from all nations. "Therefore remember that you, once Gentiles in the flesh--who are called Uncircumcision by what is called the Circumcision made in the flesh by hands-- that at that time you were without Christ, being aliens from the commonwealth of Israel and strangers from 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 by the blood of Christ. For He Himself is our peace, who has made both one, and has broken down the middle wall of separation, having abolished in His flesh the enmity, that is, the law of commandments contained in ordinances, so as to create in Himself one new man from the two, thus making peace, and that He might reconcile them both to God in one body through the cross, thereby putting to death the enmity. And He came and preached peace to you who were afar off and to those who were near. For through Him we both have access by one Spirit to the Father. Now, therefore, you are no longer strangers and foreigners, but fellow citizens with the saints and members of the household of God, having been built on the foundation of the apostles and prophets, Jesus Christ Himself being the chief cornerstone, in whom the whole building, being joined together, grows into a holy temple in the Lord, in whom you also are being built together for a dwelling place of God in the Spirit" (Ephesians 2:11-22).
Here then is the fulfillment, the peace between "natural enemies," people of differing nations, coming together in peace within the church. It has nothing to do with vegetarianism. As a matter of fact, in giving instructions to the church Paul stated concerning food, "For every creature of God is good, and nothing is to be refused if it is received with thanksgiving; for it is sanctified by the word of God and prayer" (II Timothy 4:4-5).