This matter of 'argument' is a separate matter from the necessary task of each of us reaching solid ground about our own beliefs (our basic assumptions concerning reality); the task of reaching the bedrock of what we actually do currently believe in practice -- and then discovering whether this unconscious belief of ours is something we can or should consciously embrace, or else whether it should be rejected.
Indeed, the constant concern about how we are going to convince other people, is something that poisons the whole spiritual search from the get-go.
It would be better (it is better) to do 'it' by oneself, take responsibility for oneself alone; maybe not talking about it with anyone else - certainly not trying to persuade anyone else.
These things are hard enough to put into words, but putting them into persuasive words is even more remote from the primary experience; and actually persuad-ing some other person (leave aside group!) to adopt what we personally believe, is not a matter we can control (nor should we).
(From a comment at William Wildblood's blog.)