Complex sentence: Concluding that Jesus' "chief concern was the establishment of the principles of the kingdom of God on earth," through the application of the Golden Rule, as expressed in, Nash experienced a complete change of heart regarding the theme of his upcoming sermon.
Split into simpler sentences: Concluding that Jesus' "chief concern was the establishment of the principles of the kingdom of God on earth," through the application of the Golden Rule, as expressed in. Through this realization, Nash underwent a complete change of heart regarding the theme of his upcoming sermon.