Why did the Japanese issue the Edict of 1635?

For nearly a century Japan, with approximately 500,000 Catholics by the early 1600s, was the most spectacular success story in Asia for European missionaries. Why did so many convert? Some undoubtedly were attracted by the Christian message of salvation, but others hoped to gain economic or political advantage. The daimyo of Omura seems to have converted in the hope of attracting more trade to his port city of Nagasaki, and Oda Nobunaga (1534-1582) the general who unified approximately half of Japan, encouraged Christian missionaries to undermine the political influence of the powerful and wealthy Buddhist monasteries. Nobunaga's tolerance of missionary activity was the main reason for the many converts in the region around Kyoto, Japan's imperial city.