The Rev. Charles H. Greene, pastor of Amherst Lutheran Church, shows Made line, left, and Isabel Olsen Amherst's Na tivity scene, which will spend the rest of the Christmas season on the lawn of the church on Main Street. The creche, which the Williamsville Rotary Club bought from the town, was displayed for several years in front of the Williamsville Public Library. But lawyers for the town advised the Town Board this year that it should no longer authorize use of public property because of recent court decisions that bar government endorsement of religion. The Nativity scene had been in front of the library last month before it was ordered out.