regarding your statement #1 I see in the parable of the wheat and the tares a principle of not judging before time who are the real believers. It would make better sense that the unbeliever of 7:15 is someone who never committed to Christ while his spouse did. The first church of Corinth would have such problematic situations.
Your interpretation is of special interest to me, since this is the way my wife used the verse. Even though her husband had been in the leadership of the church, he was now declared to be an unbeliever. I mean, really? So can anyone who divorces be declared an unbeliever? considering example that he does something unchristian by divorcing his wife?
Please bear with me if I include my own situation here. I hope it does not distract too much from the general line.
Regarding your statement #3, you understand "to the rest" as speaking to a specific group of people. It may be so or not be so. I mean, unmarried and married are covered, so can there be a 3rd group? It would make sense to believe that this is talking about the rest of the cases that the corinthians have asked Paul about, and that are not covered well enough by the brief statements to the unmarried and to the married.
Regarding 7:27-28, I already covered how this is speaking to the virgins. My question back to you is, how can one be a virgin if already married? ("Art thou bound to a wife") As I have already stated, I believe that "bound" in this context refers to the state of betrothal.
best regards and thanks for the conversation. Interesting to meet you.
One problem with using the wheat-and-tares parable to say the church is full of tares...
Jesus said the field is the world. Not the church. Matthew 13:38
Tares are a specific weed, which look almost identical to wheat.
But when the time of harvest comes, it's easy to tell which are tares.
Tare seed is light, so the seed stalk stands upright.
Wheat seed is heavy, so the seed heads bow under the weight.
"By their fruits you shall know them."
Jesus did not tell us that parable to say that we cannot know.
He gave that parable to tell us that the wicked will continue to exist in the world until the end, when He comes back. It's not up to the righteous, to try to root out the wicked from the world. It's a job for God. But we can tell who is real wheat, by watching for the fruit, and for humility.
As for "It would make better sense that the unbeliever of 7:15 is someone who never committed to Christ while his spouse did." Well, yes, that would be nice. But things are rarely as clean-cut as we would like for them to be.
I believe, on the basis of many scriptures (I have a list of over 30 of them) that a believer can walk away from God, and become lost. (You have "left" your first love.)
The Word is very clear: Whoever sees his brother have need, and shuts up his feelings of compassion from him, the love of God does not dwell in them. Also, anyone who refuses to provide for those of his own household, has denied the faith, and is worse than an infidel.
On the basis of these two verses, I believe we are on very safe ground to say that anyone who commits adultery/divorce, out of an unloving heart, is walking in unbelief, and is worse than if he had never believed.
I don't know how God sees those who separate under the duress of a false teaching, thinking they had to divorce, to please God. The Mennonites require such separation of ALL divorced/remarried homes.
As to who "the rest" are... I see it very clearly.
Paul says "the rest" is this:
1Corinthians 7:12 But to the rest speak I, not the Lord: If any brother hath a wife that believeth not, and she be pleased to dwell with him, let him not put her away.
1Co 7:13 And the woman which hath an husband that believeth not, and if he be pleased to dwell with her, let her not leave him.
Therefore, "the rest" are those who are married to unbelievers.
And it is obvious that this type of marriage is NOT included in "the married."
Therefore, when Paul speaks here to "the married," he means for it to be understood as "married in the Lord." (1 Corinthians 7:39)
It is obvious also that 1 Corinthians 7:27-28a is NOT speaking to virgins, but to those who are in unequal-yoke marriages. (Not in the Lord.)
Verses 25 and 26 are to virgins. But the beginning of verse 27 is the beginning of a conclusion, where he wraps up the subject of whether it's better to be married or unmarried.