I'll try, brother. First off, nobody from Adam on down is saved without the shed blood of Jesus, nobody. If God the Father had not seen the death of His Son when Adam ate of the tree of knowledge, Creation would have ended right then, in a thunderclap. But if knowledge of that fact is required, then we are not going to see very many Old Testament saints in heaven.
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Now let me give you a hypothetical scenario: While Jesus was on earth, there were Jews spread beyond the known world, in South Africa, China, Russia, England and elsewhere. They were reading "Oh how love I thy law, it is my meditation day and night" and praying to the G-d of their fathers. Those Jews didn't know that Jesus was even on the planet so they worshiped JHVH as best they knew how from Torah and the Writings. They were saved by the covenant G-d made with Abraham, Isaac and Jacob. I don't think any Bible- believing conservative theologian on earth would disagree with that.
But unknown to those diaspora Jews, the Lord Jesus went to the Cross for them, is resurrected and now sits at the right hand of Authority on high. Separated by thousands of miles from Jerusalem, they knew nothing about it.
Now here’s the question: Would those diaspora Jews who couldn't get their doctrine updated, instantly become lost the moment they came into the Christian era? If we say yes, then salvation depends on having the correct doctrinal knowledge, rather than on having a right heart towards God. If we say no, which I believe to be the correct biblical position, then Jews could be saved after the Cross without knowing Jesus as their Messiah. Point being, if a Jew could be saved for one millisecond into the Christian era without a knowledge of Jesus, then a Jew in that same spiritual condition could be saved 2000 years later. Since it is a scriptural given that God blinded the Jews to the Gospel, then like it or not, that condition does exist
So a better question would be, WHY did God blind them, rather than did it happen, because Romans 11:8 says so, but not so as those Jews would be lost, Romans 11:11.