The word "know" in 1 John 5:13 is the same word used in Genesis 4:1 where Adam "knew" his wife. It is not based on empirical data, but intimate experience. This is what gives the certainty.Cam,
You have not explained why you think my understanding of Paul in 2CR 5:6-8, PHP 1:6&14, CL 4:12 & RM 1:16-17 is incorrect, so please choose to do so.
1JN uses the terms "know" and "have confidence" interchangeably, as in 1JN 4:13&17.
Paul says we are sealed in EPH 1:13 and warns against apostasy/believing in vain in 1CR 15:2 because of failing to persevere.
Your closing question indicates that you also ignored me saying "Assured/confident, yes! (Per 2CR 5:6-8, PHP 1:6&14, CL 4:12),
but that is not knowing infallibly; we walk by faith, not by sight/proof/absolute certainty--from first to last (2CR 5:7, RM 1:16-17)."
So your use of "know" as having confidence only partially expresses the thought. That aspect is present, but it is much more than confidence; it is certainty.