There is only one Gospel Galatians 1:8
Apparently the gospel preached to Abraham and mentioned in Galatians 3:8 is the same gospel mentioned in Galatians 1:8.
Gal 3:7-9* Know ye therefore that they which are of faith, the same are the children of Abraham.
(Cambridge Bible)* Galatians 3:7
Know ye] Better indic. ‘Ye know then’. So in Php 4:15, where the punctuation in some copies of A.V. perverts the sense.
they which are of faith] This form of expression is common in Classical Greek. It means, ‘they who come from, and so belong to’; especially of persons who range themselves as members of a party or adherents of a cause. The antithesis to ‘those who are of faith’ is ‘those who are of the Law’, Rom 2:8, or ‘of the works of the Law’, Gal 3:10.
the same] Rather, these, and none others.
the children of Abraham] This was the boast of the Jews, “We have Abraham to our father”, Joh 8:39: comp. Mat 3:9. St Paul here adopts the same argument which our Lord used, “If ye were the children of Abraham, ye would do the works of Abraham’. He exercised faith in the word and promise of God. They alone ‘who have obtained like precious faith’ are the true sons of Abraham.
*(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.
(Cambridge Bible)* Galatians 3:8
St Paul’s appeal here and elsewhere to the authority of the O.T. as the unerring, irreversible decision is very instructive. This authority depends on an inspiration which is verbal, though not mechanical. The quotation combines a reference to two distinct promises, that in Gen 12:3, “And in thee shall the tribes of the earth be blessed”; and in Gen 18:18, “And all the nations of the earth shall be blessed in him”. The true seed (children) of Abraham are ‘they which are of faith’—not his natural descendants, as such, but all who, whether Jews or Gentiles, “walk in the footsteps of the faith which Abraham had in uncircumcision”.
the scripture, foreseeing] The Scripture is here personified, as in Gal 3:22. It of course means the Holy Ghost, by Whose inspiration the passage was written. In the Epistle to the Hebrews the usual formula is, ‘As the Holy Ghost saith’. Such forms of expression as ‘the Scripture said’, were common in the Rabbinic writers.
The connexion of this verse with what precedes is this:—Abraham was justified by faith, and they who are of faith are his children. But on the authority of the same Scripture we know that this filial relationship is not limited to his natural descendants, for it was promised that in him all nations should be blessed.
would justify] Pres. tense, ‘justifieth’, by an eternal law of His moral government.
the heathen] Better, ‘the Gentiles’.
preached before the gospel] Proclaimed the good tidings of justification by faith for all who believe. This announcement was made before, ‘a Gospel before Gospel times’, Bengel. Others explain it a Gospel antecedent not only to the Law, but to the institution of circumcision, Rom 4:11.
in thee] This is supposed by some to mean “as their spiritual progenitor”. Of course there is no reference to a transmitted and inherited faith. Dr Jowett’s explanation is undoubtedly right, “in thee, by anticipation”, that is, “as the progenitor of the Messiah” (Bengel). The blessing (justification) comes to man only from the atoning death and imputed merit of Christ. It was apprehended by faith in the case of Abraham; it is so apprehended by each one of his spiritual descendants. Thus, Gal 3:9, they that are of faith (note Gal 3:7) are blessed with faithful Abraham.
*(9)* So then they which be of faith are blessed with faithful Abraham.
(Cambridge Bible)* Galatians 3:9
faithful] The original word, like its English equivalent, may mean either trustworthy or trusting, deserving confidence or exercising it. In the former sense it occurs 1Co 1:9; 1Co 4:2. In the latter (which is the sense here), Joh 20:27, where it is rendered ‘believing’. The context will determine which meaning is to be assigned to it. A similar ambiguity attaches to such English words as pitiful, mournful, hopeful.