Nowadays the main reasons could be that the expansion of Christianity in Kyushu was feared to transfigure political and military aspects like Jodo Shinshu (True Pure Land Sect of Buddhism) of that time, and Christians were also regulated as 'eight schools and nine schools' (Article Nine) and Christianity was regarded as a religion under the regime in the Memorandum on June 18, but was strictly regulated again as though it would 'spread evil belief' like reversing this in the Expelling edict on June 19.
現在では主要な理由は九州におけるキリスト教の拡大が当時の浄土真宗的な政治・軍事面への変貌を危惧した事と、6月18日(旧暦)の覚書ではキリシタンも「八宗九宗」（第九条）と規定して体制下の宗教と見なしていたが、19日の追放令ではこれを覆すかのように「邪法を授け」るものとしてキリスト教を厳しく規定しなおしている。