Should we attempt to persuade each other of our ideologies? Some of us avoid proselyting. Others, such as Mormons, heartily embrace proselyting. While I don't think all forms of proselyting are good, and I don't think all ideologies (or all interpretations of any ideology) are worthy of proselyting, here are a couple reasons why we should engage in some forms of proselyting for some kinds of ideas.
In "The Superintelligent Will: Motivations and Instrumental Rationality in Advanced Artificial Agents", Nick Bostrom argues briefly for the idea that the intelligence and the purpose of an agent are mostly independent (which he calls the "orthogonality thesis"). I'm not persuaded by his reasoning. He acknowledges three constraints on the relation between intelligence and purpose, and although he characterizes them as "weak", at least two of them seem strong.
In 1978, the LDS Church extended priesthood to blacks. Prior to that time, some Mormons doubted the divinity of the priesthood ban. Subsequent to that time, some Mormons doubted the divinity of the priesthood extension. This evening, I was imagining what it might have been like in the early 1970s for a Mormon who thought blacks should receive the priesthood. What would such a Mormon have written in his journal? Here's a guess.