John 15:1-7 KJV:
“1– I am the true vine, and my Father is the husbandman. 2 Every branch in me that beareth not fruit he taketh away: and every [branch] that beareth fruit, he purgeth it, that it may bring forth more fruit. 3 Now ye are clean through the word which I have spoken unto you. 4 Abide in me, and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye, except ye abide in me. 5 I am the vine, ye [are] the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing. 6 If a man abide not in me, he is cast forth as a branch, and is withered; and men gather them, and cast [them] into the fire, and they are burned. 7 If ye abide in me, and my words abide in you, ye shall ask what ye will, and it shall be done unto you.”
For those who heard Him speak these words, the context was found in Isaiah 5:7:
Isa 5:7 KJV – 7 For the vineyard of the LORD of hosts [is] the house of Israel, and the men of Judah his pleasant plant: and he looked for judgment, but behold oppression; for righteousness, but behold a cry.
For more of the context read Isaiah chapter 5. Back in Isaiah’s time, Israel had become so corrupt that God was required to fulfill His covenant promises of dispersion and destruction. For those who knew these Scriptures and the history of Israel, they knew that the prophesies of Isaiah 5 were fulfilled when the king of Assyria invaded and conquered the ten-tribe nation called ‘Israel’ in about 722-3 BC. Many were slain; many others taken captive and were settled in Assyria; while many of the Assyrians were transferred to the land previously occupied by the ten-tribe nation of ‘Israel,’ later known as ‘Samaria.’ This resulted in a mixture of the races which in New Testament times, the Jews called ‘Samaritans,’ not recognizing them as Israelites, but rather considering them gentile dogs.
Jesus was reminding His audience of what happened to the Israel of old when they turned away from God in flagrant disobedience when He said:
“If a man abide not in Me, he is cast forth as a branch, and is withered; and men gather them and cast them into the fire, and they are burned,” John 15:6.
Tragically, multitudes of them refused to believe His warning and so men cast them into the fires of death, dispersion and destruction in 70 AD when Jerusalem was captured by the Roman armies. Millions were killed; almost another million were taken to Rome and sold as slaves, while millions more were dispersed throughout the world.
But for those who believed and heeded the words of Jesus; they were spared as a group and became the Church, the Body of Christ, the True Vine and went throughout the known world of that era, preaching and teaching the Kingdom of God in Christ.