“glorified the God of Israel.” This is a very good indication that many in the crowd were Gentiles, not Israelites. Jesus had been ministering in the region of Tyre and Sidon, Gentile areas, and had done a miraculous healing there of a demonized girl. Right after leaving there, the text says that “great multitudes” came to him, and it makes sense that many of those multitudes were Gentiles, and that was why they “glorified the God of Israel.” Matthew 15:31 is one of only two places in the New Testament where that phrase is used. “The God of Israel” was a common phrase in the Old Testament, and spoken by Zechariah at the birth of his son, John the Baptist (Luke 1:68), but it is not used anywhere else in the New Testament but those two places. When the crowds were Jews, they “glorified God” (cp. Matt. 9:8; Mark 2:12; Luke 2:28; 7:16; 13:13; 18:43; etc.).