I am sticking to God's Word, especially Apostle Paul in
Galatians 3 and
Romans 4 where he showed that Abraham's Faith on God's Promise is the SAME Faith that believers on Christ Jesus have today. Jesus showed in
John 8 that Abraham 'saw' His day, and rejoiced, and that means Abraham knew literally... The Gospel.
The difficulty is yours, with following Jewish traditions from the Pharisees who were 'against' what my Lord Jesus revealed about Abraham at the end of
John 8! They wanted to stone Jesus for pointing to them that He was there in Abraham's day!!!
What the OT reveals regarding The Gospel of Jesus Christ is that Abraham knew, and so did Enoch, the seventh from Adam, who prophesied of Jesus' future coming (
Jude 1). Even in
Genesis 18 we are shown Abraham meeting three men, and Abraham bowed to one of them calling Him Lord. Two of the men went to get Lot out, while the other stayed back conversing with Abraham, with Abraham begging to spare the righteous. That was Jesus that Abraham was conversing with, and the two men were the two angels sent to Lot's house.
So was it not possible that a chosen elect among Israel knew Christ prior to His being born through woman's womb? Yes, you betcha dollar! The OT prophets bear witness to it.
Did the OT prophets declare The Gospel of Jesus Christ also, which is about God's Promise to send a Saviour? Yes, that is emphatically written in the OT prophet of Isaiah, even to where He would be born (
Micah 5:1). And David would be given the events of Christ's crucifixion, even about the casting of lots upon Jesus' clothing, and that was about a thousand years before it happened, Jesus quoting from it while on the cross (
Psalms 22).
Then there's the matter of God's Birthright promises. Those BEGAN with Abraham based on his Faith on God's Promise. And those birthright blessings then continued to Isaac, then to Jacob, then to Joseph, and then to Joseph's two sons Ephraim and Manasseh, where God's Birthright STILL exists today, but not upon unbelieving Israel, but upon believing Israel, Christ's Church! This is why there is no more king of the house of David in Jerusalem today! The Gospel was ALWAYS part of God's Birthright blessings first given through Abraham with his belief on the Promise by Faith. Heck, that belief, even by faithful Abraham, IS about belief on The Gospel of Jesus Christ!