Would you like to construct a sentence using this phrase? We shall see if it is correct. I shall do one first. I shall start with: There are many influential institutions which are against marriage for all. Then I try to think of the one which is the most strongly opposed to it. Then I add it to my original sentence. It becomes: There are many influential institutions which are against marriage for all, none more so than the Catholic Church, which believes that marriage should only be between a man and a woman.

We use "none more so than..." to express the person or organisation that are the most surprised with a result. Many people thought I'd fail, none more so than me. (Many people thought it, but I thought it the most).