The problem with 'should' and particularly with unconditional should is that it is an imposition. If we should 'respect' everybody because they are humans maybe we should also 'love' everybody too. The fact is we love only what is 'loveable' the same way that we respect only what is 'respectable'. No amount of 'should' can change that.

I can respect 'anyone' who displays respectable charecteristics but I cannot and do not respect people just because they belong to the human race.  

I am not sure that people whose lives are dominated by 'belief' would agree with your assertion that 'beliefs are fragile things and not a profound part of the person.' If anything we have all the evidence to the contrary. The human being is a very belief orientated creature and it is in belief that s/he finds consolation and a purpose and meaning in life. All believers believe in the universality of their beliefs/experiences and consequently feel a sense of superiority to other humans. Out of this sense of superiority comes the need to spread their belief if necessary by force.

You say 'argument is a rather poor way to get people to relinquish their beliefs' and offer as an alternative  the loving heat of the sun to do the job. I disagree. Argument is the 'best' way to get people to examine and hopefully change their views. If argument was indeed so ineffective why do 'all' believers are advised to avoid it?

I think we are all believers and if we value growth (which means change) we all (including premies)have to 'welcome' a healthy disrespect for our beliefs from our fellow humans.