Since Soka Gakkai members, for the most part, are persons of benighted comprehension who lack learning, they will not listen to reason

"You should keep using their own words again and again in this fashion to drive them into a corner. However, since they lack all learning, they will not listen to reason. They cannot understand the reasoning of others, nor do they understand the flaws in their own reasoning; they are persons of benighted comprehension. And since they refuse to bow to reason, addressing them is like trying to paint a picture on flowing water." - Nichiren