If that parable really illustrated two separate people in the Calvinistic sense required, the apostles and disciples would not have misunderstood the parable so as to need explanation. “Whenever anyone hears the word of the kingdom and does not understand it”, they are like the ones on whom seed is sown by the road. All the apostles and disciples ended up having no firm root and fell away immediately (though to various degrees) when persecution arose–and this was after having the parable explained to them! So they were ones on whom the seed was sown in rocky places.
Again, Peter routinely had problems realizing he was supposed to be evangelizing Gentiles not only Jews, and wasn’t called to make converts to Judaism per se. St. Paul had some sharp things to say about him being afraid of the opinion of others!–and that was all well into the post-resurrection ministry! He (if not the others) counts as one on whom the seed was sown among the thorns.
Moreover, Jesus shifted over to parables (as GosMatt makes clearer than the other Synoptics) the afternoon after the Pharisees of Capernaum had charged Him with serving and healing by the power of the devil, when He had healed a man from whom (as Matthew also somewhat clarifies) He had already cast out one demon and who had come back with his latter state worse than his first: the Pharisees are condemned for being willing to contradict their own principles in order to put limits on God’s salvation of people from sin, so I’m loath to interpret Jesus’ parables (and His interpretation of parables) with limits on His salvation of people from sin!
The parable of the wheat and the tares speaks of “sons of the kingdom” being in the group that Calvs would regard as the elect, thus the other group as the non-elect; but the previous time in GosMatt (8:12) Jesus had spoken of “the sons of the kingdom”, He was warning them that they would be wailing and gnashing their teeth about being thrown outside and seeing people they weren’t expecting to be saved entering into the kingdom to dine with the patriarchs at the table of the Lord!
So again, there isn’t two separate people in the sense required by Calvinism. “The sons of the kingdom” may be “sons of the evil one” and punished thereby.
(To which could be added that the parable portrays God being caught by surprise and the tares being something God can do nothing about. So even Calvs must acknowledge the details shouldn’t be held to rigorously: it isn’t as though God graciously transforms the tares into wheat.)
In regard to the wheat and chaff (which comes from Matt 3, not Matt 13, paralleled at Luke 3:9,16-17): Jesus isn’t simply dividing completely separate items from each other, wheat and chaff, but is removing each kernal of wheat from its own chaff by scouring with the winnowing fan. This tends to imply salvation of a person from sin, not separation of different kinds of person.
John the Baptist, in teaching this parable, connects it to Malachi 4:1-3, which features similar imagery attributed as part of the message of the coming Elijah, including burning of the tree (per Luke 3:9 and Matt 3:10). However, God (via Malachi) says this is coming to all sinners on the Day of YHWH to come; but all sinners must include the rebel Israelites (particularly the rebel religious leaders–who are specifically whom JohnBapt is admonishing in GosMatt and GosLuke) from back in Malachi 3, who are set to be purged with fire in the same Day of YHWH to come. This is very far from hopeless for them, as God both intends to save them from their sins thereby (in refining imagery) and prophetically expects full success! This lends great strength to the interpretation of the chaff as being salvation of sinners from sin: the Synoptic saying, in its referential contexts, testifies at least to the salvation of rebel Israel in the Day of YHWH to come, with the implication that this applies to all sinners via Mal 4.
Actually, in the parable the good fish are slated to be thrown into the fire after being stored in containers; the bad fish are thrown away, presumably back in the lake!
Jesus reverses the actual imagery somewhat, with the explanation being that the bad fish are thrown in the fire (where, per Matt 8:12, the sons of the kingdom will also be thrown if they don’t cooperate with God bringing in people whom the sons aren’t expecting to be brought in!) If the lake == hades/Gehenna, which would be typical Jewish poetic imagery, that means the good fish as being saved out of the spirit prison but others thrown back in. That would run rather counter to the notion that the good fish don’t go to spirit prison in the first place, and tends to suggest salvation of penitent post-mortem spirits. Which (as I noted earlier in another thread) could work with Calvinism, too, so long as the Calvinist allows post-mortem salvation of the elect. But the details of the parable subtly undermine any notion of two absolutely separate people in the Calvinistic sense required. Unless Calvinists are saying that God only saves people who are already good enough to be saved to begin with (which Calvs strongly argue against vs. the implications of Arm soteriology).
The most that can be said for sure of the parable is that it teaches punishment of the wicked eventually in fire and with weeping and gnashing of teeth, which is a belief Arms and (purgatorial) Kaths share with Calvs. What it means for them to be so punished has to be established elsewhere. (But mustn’t involve denying that God is able and willing to save those whose latter states are worse than their former.)
The baby-goats are explicitly described as being part of the flock of the shepherd, and so are literally the least of Christ’s flock (although they didn’t think so and weren’t interested in saving who they thought were the least of Christ’s flock).
Any interpretation that involves a hopeless fate for the goats requires that the Good Shepherd and the good flock (since the term there can include goats as well as sheep) will proceed to treat the least of Christ’s flock the way the least of Christ’s flock treated the least of Christ’s flock for which the least of Christ’s flock are being sent into the eonian fire and kolasis prepared for the devil; which is an interpretation of the sort a baby-goat would make! (The baby-goats are explicitly the ones who think in terms of people to be saved and people not to be saved.)
Considering that this parable caps a trio of warnings where the other two parables involve lazy and/or uncharitable servants of Christ (the foolish virgins are not part of some separate group who don’t belong to the bridegroom; the lazy investor who tries to get out of his duty by flattering his master as a chief of brigands isn’t some separate group of person), and considering that Christ counts those among His mature flock who didn’t even know they were serving Christ (while the baby-goats are surprised to hear they weren’t serving Christ), I take that judgment parable very, very seriously: on the basis of that judgment alone, I would be extremely leery about interpreting anything else Christ said to involve hopeless punishment of anyone, on pain of being judged by Christ myself to be only a baby-goat. (Although fortunately the problem appears to be an attitude of the heart on the part of the baby-goats, not a technical misunderstanding. )