I haven't been doing this as long as you have ("only" 20 years), but I occasionally have seen people change their point of view as a result of these discussions. It's rare. I don't know if that counts as "conversions".
Let’s include that scenario in our discussion. Changing our minds about anything = a conversion.
There are atheists on the Board. Agnostics, Jews, Muslims, Christians of various types and doubtless other faiths too. Are any of them here with the intention of converting others to whatever it is that they believe is true?
And over those 20 years, I've changed too. More evolutionary than revolutionary, but ... something is at work.
I’ve also changed my mind, occasionally, in response to something I’ve read on internet discussion forums; just as I have when reading books. Sometimes it is in regard to theology, but it can also be regard to any other matter being discussed (finances, parenting, work, technology, etc.)
Most of what I read on internet discussion forums concerning theology - as opposed to what I read in books concerning theology - causes me to close my mind.
Why is that?
I attribute it to the toxic nature inherent in online discussion forums - where people frequently throw off all restraint and show us who they really are behind the anonymity of the screen.
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So, to those who are here with the intention of converting people to whatever: your attitude is, or may be, causing people to close their minds.
Rate of successfully converting a closed mind? 0%.
Internet discussion forums -> sowing your seed on hard ground. (My Christian readers will, I trust, see this as an intentional allusion to the parable of the sower.)