Abraham’s household, Isaac and his son Jacob etc, all before the OT. The faithful Israelites without the Torah. The faithful of Israel prior to Christ. Not rare at all.
I assume you are being sarcastic.
How many men were told to sacrifice their own son on the altar?
It hit him at a very personal and experiential level. And they were not told of the saving grace through the death and resurrection of Christ. Abraham’s faith is what mattered, but not from a Christian perspective. There was no such thing as a Christian until Jesus was raised from the dead.