In the parable or illustration of the "wheat and weeds"(tares, King James Bible) at Matthew 13:24-30, Jesus likens the "kingdom of the heavens" to a "man that sowed fine seed in his field" and which was later 'oversowed with weeds in among the wheat' by an "enemy", with him providing an explanation at verses 36-43. This parable or illustration is also interconnected with the illustrations of the "mustard grain" at verses 31,32, the ' woman who mixed leaven in with her flour '(meal, King James Bible) at verse 33, and with the "dragnet", at verses 47-50.
In the fall of 29 C.E., not long after Jesus baptism, he began to make known the "good news of the kingdom", saying: "The appointed time has been fulfilled, and the kingdom of God has drawn near."(Mark 1:14) And over the course of his 3 1/2 year ministry, he repetitively emphasized the "kingdom", a heavenly government, using many an illustration to teach regarding it's truths and that God conceived, following Adam's rebellion in the Garden of Eden.(Gen 3:15) The unveiling or revealing of the "kingdom" began to occur over a period of some 4000 years. But with the arrival of Jesus as the Christ in 29 C.E., the "kingdom" was now explained with the use of illustrations. Thus, Jesus established truths concerning the "kingdom", with those accepting these truths being the "fine seed".(Matt 13:24)
However, in the parable or illustration of the "wheat and weeds", Jesus expected a change regarding the "kingdom". In his illustration, he says that following the sowing of the "fine seed", the "sons of the kingdom"(Matt 13:38), by the "Son of man" Jesus Christ over 3 1/2 years (Matt 13:37), he then says that "while men were sleeping, his enemy came and oversowed weeds (Greek zizanion, tares, King James Bible, "sons of the wicked one"[Matt 13:38]) in among the wheat, and left."(Matt 13:25)
Jesus most likely referred to the poisonous bearded darnel (Lolium temulentum), which it's poisonous properties are believed to stem from a fungus growing within it's seeds and closely resembles wheat until maturity. At this time, it can readily be distinguished from wheat by it's smaller black seeds. This, together with the fact that the roots of these "weeds" become entwined with the wheat, would make it most inadvisable to pull up the "weeds" at an early stage.Thus, in giving direction to the "slaves of the household", the "master" told them to let both the "wheat" and "weeds" grow together, "that by no chance while collecting the weeds, you uproot the wheat with them."(Matt 13:29,30) Thus, a considerable period of time would pass until it was time to ' collect the weeds '.
Who though, is the "enemy" that sowed "weeds" in among the "wheat" ? Jesus identifies him as "the Devil". Thus Satan, after Jesus had laid out the principles and foundation of the "kingdom" while on the earth, began to infiltrate the "kingdom", using "weeds" or "sons of the wicked one." How ? The apostle Paul, in giving parting counsel to the older men from Ephesus, said: "I know that after my going away oppressive wolves will enter in among you and will not treat the flock with tenderness, and from among you yourselves men will rise and speak twisted things to draw away the disciples after themselves."(Acts 20:29,30)
Hence, not long after, from within the the Christian congregation, there arose men ("weeds", "tares") who began to speak "twisted things", distorting the teachings of Jesus Christ. These professed to follow Jesus, but instead were counterfeit Christians that began to grow within the congregation that Jesus had established, even while the apostles were alive.
The apostle Peter wrote to fellow Christians, in about the year 64 C.E., that "there came to be false prophets among the people, as there will also be false teachers among you. These very ones will quietly bring in destructive sects and will disown even the owners that brought them,...Furthermore, many will follow their acts of loose conduct, and on account of these the way of the truth will be spoken of abusively. Also, with coventousness they will exploit you with counterfeit words."(2 Pet 2:1-3)
Peter, was thus warning true Christians that there would be a "falling away" or apostasizing (Greek a·po·sta·siŽa, literally "to stand away from", and has the sense of "desertion, abandonment or rebellion." [Ac 21:21]), of the teachings of Jesus. From within the Christian congregation would this occur, for both Paul said that "from among you yourselves men will rise and speak twisted things", and Peter said that "false teachers (will be) among you" that will "quietly bring in destructive sects". Especially following the death of the last apostle, John, in about 100 C.E., did this "falling away" or apostasizing begin to flourish, as Jesus said, "while men (the apostles) were sleeping". There was now practically no one to restrain or hold back this wave of apostasy.
The apostle John, in about 96 C.E., wrote: "Young children, it is the last hour, and, just as you have heard that antichrist is coming, even now there have come to be many antichrists; from which fact we gain the knowledge that it is the last hour."(1 John 2:18) Hence, even at that "last hour", true Christianity was being overtaken by the "antichrists"(meaning "against [or instead of] Christ)", "weeds", counterfeit Christians.
Within a period of less than 300 years from the time that Jesus established the Christian congregation, the wheat field of Christianity had been overrun with the "weeds" of apostate antichrists to the point where Constantine the Great (himself incriminated in the murder of no less than seven close friends and relatives) figured in events that led to the development of a state religion disguised as "Christianity", with the Council of Nicaea in 325 C.E.
Hence, there arose a "leavened" or apostate Christianity, one that is corrupted.(Matt 13:33) It is flourishing as the churches of Christendom, for just as the "mustard grain" grew into a "tree", the individual religious organizations (churches), that profess to be Christian, are like the "birds of heaven", with each one finding "lodging among (Christendom's) branches".(Matt 13:32)
A prophesy by Isaiah directs one's attention that true Christianity, though infiltrated with "weeds" during the course of over 1900 years (' growing together until the harvest',Matt 13:30), from the days of the apostles, would once again be reestablished in the "final part of the days", our time period. Isaiah was inspired to write: "it shall come to pass in the latter days, that the mountain of Jehovah's house shall be established on the top of the mountains, and shall be exalted above the hills; and all nations shall flow unto it. And many peoples shall go and say, Come ye, and let us go up to the mountain of Jehovah, to the house of the God of Jacob; and he will teach us of his ways, and we will walk in his paths: for out of Zion shall go forth the law, and the word of Jehovah from Jerusalem. And he will judge between the nations, and will decide concerning many peoples; and 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 any more."(Isaiah 2:2-4, American Standard Version)
During the "latter days", our time period now, angels will soon ' collect the weeds and burn them with fire ', these to be destroyed (Matt 13:39,40), during which time "the righteous ones will shine as brightly as the sun in the kingdom of their Father."(Matt 13:43) Hence, true Christianity would once again flourish in these "latter days", even though "weeds", counterfeit Christians, are still abounding until God's time to have these "collected and burned with fire" during the "conclusion of a system of things".(Matt 13:40, "end of the world", King James Bible)
Thus, Jesus fully expected true Christianity to be corrupted and gave several illustrations that showed this. We are now living during the "harvest" or "conclusion of a system of things" and thus God is soon to destroy the "weeds" or "tares", counterfeit Christians and whereby true Christianity would be clearly discernible for honest-hearted persons.