Complex sentence: The main organization of the latter was the 8 May movement, (Dutch: "Acht Mei-beweging") that was founded and 1985 initiated by the disputes about the papal visit in that year to the Netherlands.
Split into simpler sentences: The main organization of the latter was the 8 May movement, (Dutch: "Acht Mei-beweging") that was founded in 1985. Its founding was initiated by the disputes about the papal visit in that year to the Netherlands.