A dispensational dilemma

The great commission was & is still future yet, God's plan to bless the world through Israel. Why is it then that the vast majority of evangelicals insist on saying that the great commission is our marching orders? Have we yet to realize that the nation of Israel never fulfilled the great commission? It was God's plan and purpose, that through the nation of Israel, salvation would then reach the rest of the Gentile world.

But every student of the Bible knows the story, that Israel as a nation rejected Christ as their Messiah and God have set her aside for a time in unbelief. He then saves Saul of Tarsus and uses him to usher in the present dispensation of grace. Now there are many Bible teachers who are aware of this and they also know that the terms and conditions of salvation under grace does not fit in with the terms and conditions of the great commission. So they run over to Paul's epistles in 1 Cor 15 vs 1 – 4, and borrow the terms of salvation and then run right back to the four Gospels and the book of Acts and say herein lies our marching orders for the Church today, and it has caused nothing but total confusion.