As he exits the stage before any votes are cast, Chris Christie deserves credit and thanks for repeatedly saying what Republican primary voters need to hear. Donald Trump is unfit for office. Christie preached it wide and far, eloquently, reasonably and courageously. The former New Jersey governor, who backed Trump’s campaign when the real estate mogul improbably won the presidency in 2016, refashioned himself for this cycle as a GOP voice in the wilderness, speaking harsh truths both to the primary electorate and to rivals vying for the nomination. There were some who looked upon his campaign…