But contrariwise, when they saw that the gospel of the uncircumcision was committed unto me, as the gospel of the circumcision was unto Peter [Gal. 2:7].

Let’s understand that there were not two gospels in the sense of Peter’s gospel and Paul’s gospel. These men were in complete agreement. The gospel of the circumcision and the gospel of the uncircumcision refer to the groups the gospel was going to. The Gentiles were the group that Paul was speaking to. He was called to go to the Gentiles, the uncircumcised. Peter was called to go to his own Jewish brethren who were the circumcised.

(For he that wrought effectually in Peter to the apostleship of the circumcision, the same was mighty in me toward the Gentiles:) [Gal. 2:8].

The proof of the pudding, of course, is always in the eating. What results were they getting? When Peter preached the gospel, quite a few people were saved. When Paul preached the gospel, quite a few people were saved. They were both preaching the same gospel.
Now bringing this principle down to where we live, the real test of any Christian work is not promotion. The real test is the result it gets. God’s people should be very sure that they are supporting a ministry that gets results. If it is not producing results, why in the world do you support it? McGee, J. V. (1991). Thru the Bible commentary: The Epistles (Galatians) (electronic ed., Vol. 46, pp. 30–31). Nashville: Thomas Nelson.

Ga 2:7 The Judaizers claimed Paul was preaching a deviant gospel, but the apostles confirmed that he proclaimed the true gospel. It was the same gospel Peter proclaimed, but to a different audience. for the uncircumcised. Better translated “to the uncircumcised.” Paul preached the gospel primarily to the Gentiles (also to Jews in Gentile lands, as his pattern was to go to the synagogue first; cf. Acts 13:5). circumcised … Peter. Peter’s ministry was primarily to the Jews.
2:8 He who worked effectively in Peter … in me. The Holy Spirit, who has but one gospel, empowered both Peter and Paul in their ministries. MacArthur, J., Jr. (Ed.). (1997). The MacArthur Study Bible (electronic ed., p. 1790). Nashville, TN: Word Pub.