I don't know why most main-line churches are anti-Israel, but they are. They need to look at a map and see what surrounds our tiny ally, Israel. Pro-abortion, anti-Israel, pro-feminist, pro-LGBTQ agenda, pro-Democrat, pro-BLM, pro-illegal immigration, and that just about sums up the political agenda of many "Christian" churches. If you left the church years ago because there was too much "come to Jesus" preaching about sin and not enough about social justice, take a second look. There's something for you if you're missing pot lucks and Sunday School.
This item is about ELCA (Evangelical Lutheran Church in America) the synod our local congregation left about 5 years ago (now NALC), but it's no different in Church of the Brethren, United Methodist, United Church of Christ, etc.
"The Evangelical Lutheran Church in America (ELCA) has approved two resolutions advanced by anti-Israel activists including a push to end all U.S. aid to the Jewish state until the “military occupation of Palestinian land” ceases, according to CBN News. The resolution was adopted in an overwhelming 751 to 162 vote during the Mainline Protestant denomination’s triennial Churchwide Assembly held in New Orleans August 8-13." https://juicyecumenism.com/2016/08/15/lutherans-israel-resolutions/