Complex sentence: The first kings of Mercia were followers of Woden and other Anglo-Saxon gods, and they resisted the encroachment of Christianity longer than any other kingdom in the Anglo-Saxon Heptarchy, and remained resolutely pagan until the reign of Paeda in 656.
Split into simpler sentences: The first kings of Mercia were pagans, and they resisted the encroachment of Christianity longer than other kingdoms in the Anglo-Saxon Heptarchy. Mercia remained resolutely pagan until the reign of Paeda in 656.