The minister, the Rev. Greg Dell, 53, has been formally charged with disobedience to Methodism's "order and discipline" for having blessed the union of two men in his church, Broadway United Methodist Church, here in Chicago last September. The trial will begin on Thursday, with 13 ministers acting as a jury and a retired bishop as judge, in a church sanctuary in suburban Downers Grove. A verdict could come on Saturday. Conviction could lead to loss of his ministerial credentials.