I have no problems with choosing not to invest in Israel.
It isn't like we don't send at least $3 billion a year in foreign aid since 1987...
Leaving aside the question of investing in Israel, they are divesting from UYS companies that do business with Israel and, in particular, help it defend its citizenry from terrorism. For example, an often-mentioned target of the divestiture crusade (even by a PCUSA minister who posted on Free Republic) was Caterpillar, because it sells bulldozers to the IDF, which the IDF uses to close weapon-smuggling tunnels.
They are trying to pressure American companies to abandon Israel's efforts to defend itself against Palestinian arab terror.