Complex sentence: Experts that have studied the church believe that the church was first built in the old style and that the structure's style and details suggest that it is one of the oldest existing churches in Norway today.
Split into simpler sentences: Experts that have studied the church believe that the first church was built in the old style and that it may be one of the oldest churches built in Norway. The structure's style and details suggest that it is one of the oldest existing churches in Norway today.