First, what I'm saying about Matthew 24:12 KJV is not conjecture; it's a fully Biblical, hermeneutical conclusion.
Here's what I think your perspective is so far (P=point, C=conclusion, R=rebuttal):
P1) Only saints and God have agape
P2) Those with agape are saved
P3) It is possible to lose agape
C1) Therefore, OSAS (once saved, always saved) is necessarily false
R1) I have no disagreement with points 1 and 2, but point 3 is not demonstrated and further contradicts 1 Cor 13:7, therefore the conclusion is incorrect.
P3.1) The loss of agape is demonstrated in Mat 24:12 by the term "cold" agape and necessarily means "dead"/"lost" agape.
P3.2) Cold agape is parallel to spitting out the lukewarm
P3.3) Splitting out the lukewarm necessarily means rejection and loss of salvation
P3.4) Mat 24:12 is necessarily describing a different set of people than Mat 24:12
C3.X) Therefore, Point 3 is necessarily true
R3.1) Point 3.1 has no scriptural basis, and therefore is not necessarily true. Further, other passages speak contrary to this interpretation. An apostate is considered to have "never really been one of us to begin with" in 1 John 2:19.
R3.2) Point 3.2 could be true
R3.3) There are two interpretations that could be applied to splitting out: a) loss of salvation, and; b) a requirement for purification. Purification is demonstrated in scripture, loss of salvation is not. There is enough information to substantiate the purification interpretation, there is not enough information to substantiated the loss of salvation interpretation.
R3.4) Point 3.4 has also not been demonstrated to be true.
R3.X) The conclusion is false as a result of the points not being demonstrated to be necessarily true.
Others who recognize how nonsensical that idea is admit these "many" are Saints, but deny Jesus' clear contrast of the fates of those in verse 12 and 13 - the one "saved" and the other obviously not saved. If Jesus didn't mean that, what purpose does His statement serve? Why would he say, "My children, because of iniquity, some of you will continue to be on fire while some of you will fizzle, but you're all still going to heaven"
This is an example of an interpretation (and paraphrasing therein) that is not demonstrated to be necessarily true. The concept that verse 12 and 13 are talking about separate groups of people needs to be demonstrated. Especially when compared to "I would rather you were hot or cold" from the spitting out the lukewarm passage.
This is how TPT phrases the remark about hot or cold:
"I know all that you do, and I know that you are neither frozen in apathy nor fervent with passion. How I wish you were either one or the other!" - Revelation 3:15 TPT
there are several examples of Saints that will not make it to heaven in the OT and NT.
I have not seen any scripture that says this. Yes, I am interested to see if there are any. This would help your point greatly if they are in proper context. I do not see your interpretation of Mat 24:12-13 as being in proper context. I look forward to seeing your other examples.