A left-wing charity organization with unknown sources of money is providing the funding for protests around the country — some of which have turned into violent riots — that have threatened a divided nation’s ability to unify after a contentious presidential election. The Progress Unity Fund is a tax-exempt 501(c)3 organization — the same classification as the Red Cross. The group’s mission is to “provide a progressive alternative to mainstream charities,” according to its IRS filings. The fund provides the financial backing for Act Now To Stop War & End Racism (ANSWER) Coalition, a left-wing activist group that began organizing...