For in one Spirit we were all baptized into one body—Jews or Greeks, slaves or free—and all were made to drink of one Spirit.
1 Corinthians 12:13

Paul wrote that Jew and Greek, slave and free, male and female are all one in Messiah. We are all equally "saved". It has always been that way. Abraham, Caleb, and Rahab were all equally God's chosen people by their faith in his salvation despite having not been born as Israelites. This didn't change at the cross or pentecost.

It also doesn't mean there are no more distinctions between Jew and Greek, slave and free, male and female. Equality in one respect does not mean--or even imply--equality in any other respect, as the rest of this chapter and Paul's other writings makes abundantly clear.