Data point: After years of having the correct arguments in my hand, having indeed generated many of them myself, and simply refusing to update, Eliezer, Cectic, and Dan Meissler ganged up on me and got the job done.

I think Jesus and Mo helped too, now I think of it. That period's already getting murky in my head =/

Anyhow, point is, none of the above are what you'd call gentle.

ETA: I really do think humor is incredibly corrosive to religion. Years before this, the closest I ever came to deconversion was right after I read "Kissing Hank's Ass"

I'd guess aggression would have a polarising affect, depending upon ingroup or outgroup affiliation.

Aggression from an member of your own group is directed at something important that you ought to take note of. Aggression from an outsider is possibly directed at you so something to be ignored (if not credible) or countered.

We really need some students to do some tests upon, or a better way of searching psych research than google.

These results seem to support that, though there have also been contradictory reports from people saying that the very aggressiveness was what made them actually think.

Presumably there's heterogeneity in people's reactions to aggressiveness and to soft approaches. Most likely a minority of people react better to aggressive approaches and most people react better to being fed opposing arguments in a sandwich with self-affirmation bread.

I have long been thinking that the openly aggressive approach some display in promoting atheism / political ideas / whatever seems counterproductive, and more likely to make the other people not listen than it is to make them listen.

I believe aggressive debates are not about convincing the people you are debating with, that is likely to be impossible. Instead it is about convincing third parties who have not yet made up their mind. For that purpose it might be better to take an overly extreme position and to attack your opponents as much as possible.

I think one of the reasons this self-esteem seeding works is that identifying your core values makes other issues look less important.

On the other hand, if you e.g. independently expressed that God is an important element of your identity and belief in him is one of your treasured values, then it may backfire and you will be even harder to move you away from that. (Of course I am not sure: I have never seen any scientific data on that. This is purely a wild guess.)