Complex sentence: The practice of worship on these spots, though after the temple was built it had been forbidden, became frequent among the Hebrews, and was with difficulty abolished, though denounced time after time by the prophets as an affront to God.
Split into simpler sentences: The practice of worship on these spots became frequent among the Hebrews, though after the temple was built it was forbidden. Such worship was with difficulty abolished, though denounced time after time by the prophets as an affront to God.