I think you need to reread the Book of Acts. What you are referencing was Paul who was called to the Gentiles. Peter and James were quite successful with the Jewish people:Actually no. The disciples struggled greatly converting jews, because a crucified messiah (an oxymoron, to a Jew at that time) was a total non-starter Their message, as Paul admitted, a stumbling block to Jews. Its what got Paul kicked and strapped and chased all over the place every time he'd try to talk about it. The early Christians enjoyed their greatest success converting gentiles, this has ben well-documented by several studies (i.e. the demographics of the rising Jesus movement)).
Acts 6:7
Then the word of God spread, and the number of the disciples multiplied greatly in Jerusalem, and a great many of the priests were obedient to the faith.
"Multiplied greatly" doesn’t mean a few.