The gospel (glad tidings of great joy) would be preached among the Jews; they would reject it and reject their Messiah. They would have him killed, and after he rose from the dead he would make himself manifest, by the Holy Ghost, to the Gentiles—which manifestations are recorded in the New Testament books of Acts through Revelation.
The term Gentiles is used many times from this point on in the Book of Mormon, so it would be wise to define its meaning: “During the meridian dispensation … the gospel went preferentially to the Jews first and to the Gentiles second. In the final dispensation the order would be reversed. Note again that to the Nephites, Jews were nationals, persons from the kingdom of Judah. In this sense, the Nephites and Lamanites—though genealogically of the tribe of Joseph—were Jews (see 2 Nephi 30:4; 33:8). Gentiles were all other peoples, including those who were of the house of Israel but who would be found among other nations on earth… . In this sense, the Latter-day Saints are called Gentiles (see D&C 109:60).” 23