The pilot and two passengers were flying to an airport to pick up a friend. Night VMC prevailed. Witnesses observed the airplane flying at about 300 ft AGL at various positions over the city, varying headings, and sometimes circling. One witness stated that the pilot 'seemed like he didn't know where he was going.' The airplane then proceeded toward the midfield point of the airport on a northerly heading. It collided with pine trees, then fell into the roof of a church located 150 feet farther north. The aircraft, and church, were destroyed by fire. The fuel selector valve was found in the 'left aux' tank position; however, aux tanks were to be used in level flight only. Actuator settings indicated the gear was down & the flaps were up. Prop signatures indicated prop rotation in a power producing mode at impact. The runway lights for RWY 9/27 were on at the time, and the aircraft's northerly heading was not aligned with any runway. The location of the airport did not require the city to be overflowed.