Peter told about non-Jews becoming believers when he preached to them.

Acts 15:6-11

6 Then the apostles and the other elders met together in order to talk about this matter. 7 After they had discussed it for a long time, Peter stood up and spoke to them. He said, “Fellow believers, you all know that a long time ago God chose me from among you other apostles, in order that the non-Jewish people might also hear me [SYN] tell them the good message about the Lord Jesus, so that they could hear it and believe in him. So Paul and Barnabas are not the first ones to tell non-Jews about Jesus. 8 God knows and judges people according to what they think, not according to who their ancestors were. By sending the Holy Spirit to the non-Jews, just like he had also done for us (inc) Jews, he showed me and others that he had accepted them also to be his people. 9 God saved us Jews and those non-Jews similarly, making them clean spiritually simply as a result of their believing in the Lord Jesus. That was exactly how he has forgiven us. 10 You are wanting to force the non-Jewish believers to obey our Jewish rituals and laws—laws that God has shown that he does not require them to obey [MET]. Your doing that is like putting a heavy burden on them! So then, ◄stop making God angry by doing that!/why are you making God angry by doing that?► [RHQ] Our ancestors and we (inc) Jews have never been able to bear the burden of obeying those laws! 11 But we (inc) know that it is not because we (inc) try to obey those laws that God saves us(inc) Jews. On the contrary, we (inc) know that it is because of what the Lord Jesus did for us (inc) that we did not deserve that we (inc) are saved {that God saves us} from the guilt of our sins. God saves non-Jews who believe in the Lord Jesus exactly like he saves us Jews.”