The cross of Christ is foretold in Old Testament prophecy, and through types and shadows. The Old Testament Scriptures always looked forward. It was the Spirit of Christ who testified.
1 Peter 1:11 Searching what, or what manner of time the Spirit of Christ which was in them did signify, when it testified beforehand the sufferings of Christ, and the glory that should follow.
The Gospel was preached to Abraham in the Old Testament.
Galatians 3:8 And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed.
Genesis 12:3 And I will bless them that bless thee, and curse him that curseth thee: and in thee shall all families of the earth be blessed.
Notice … Scripture says “all nations” and “all families.” This foretells Gospel times, but it is also very true that the Lord always embraced all who would embrace Him. It was not being Jewish by race that made someone a child of God, even in the Old Testament. It was always a matter of faith. Taking Scripture out of context, and taking the “all” out of the Old Testament is no doubt a very serious matter. This is what Christian Zionists have done with Genesis 12:3, and it is a deadly mistake.