A former employee has sued Northbrook-based Allstate Insurance Company for discrimination, maintaining he was fired for writing an Internet-published essay that slams same-sex marriage and homosexual lifestyles. J. Matt Barber, 35, of Villa Park, said last week his Christian faith led him to write the essay in December 2004, on his own time and at home. His federal lawsuit alleges Allstate officials told him the following month that he was being suspended for writing the piece. He was fired three days later. Barber's lawsuit claims his dismissal violates his constitutional right to free exercise of religion and seeks an unspecified...