What is the crime of Philistia that really shows her sinfulness? “They carried into exile a whole people to deliver them up to Edom.” This likely refers to border raids (into Judah and into Israel) whereby people would be captured and then sold to the Edomites as slaves who in turn bought these slaves for their own usage or to be sold on the world market.
Especially for God’s people this was horrible! These captives were thereby excommunicated against their will out of God’s special saving nation in this world! That is why within Israel, if an Israelite ever became a slave to another Israelite due to poverty, he was not allowed to be sold outside the borders of Israel.
No, our God does not take it lightly when barriers are erected to his people being part of his people. We can think of persecution, whereby Christians are forbidden access to the worship services. How that provokes our Lord to anger! How dangerous this is for those doing the persecuting—they will face special wrath!
When God’s people are persecuted (and thus also prevented from integrating with his people and worshipping together with them), then our God takes that very personally! He might not take action right away, but in due time he will act and he will vindicate!
6 Thus says the LORD: “For three transgressions of Gaza, and for four, I will not revoke the punishment, because they carried into exile a whole people to deliver them up to Edom.