It is hard to separate political issues from moral ones these days. Churches should speak out on moral issues. Their moral and charitable missions (e.g. speaking out on child separation policy at the border, running homeless shelters) are worthy of tax exemption. However, political activities (e.g. supporting specific politicians) run counter to this and if clearly proven should be cause for removal of tax exempt status. But the IRS would have to investigate and court dockets would be swamped.