Should we take words seriously? Absolutely! And I will at the outset present the Word of Allah Himself, showing how important the choice of words is:
2:104
O you who have believed, say not [to Allah 's Messenger], "Ra'ina" but say, "Unthurna" and listen. And for the disbelievers is a painful punishment.
So yes, words matter, especially when the subject matter is religious. Now, unfortunately, there is a lot of blasphemous content on the internet which misguides people. It is perfectly OK for someone to quote such content, or even post something that comes to his own mind, to seek the opinion of Muslims. If his intention is to gain knowledge and understanding, then it is OK. But blatant denigration of anyone's religion is intolerable.
This raises the interesting case of Qadiyanis. Here is a 'so called' religion whose fundamental belief is blasphemous towards Islam, and who likewise consider it blasphemy if they are called out and negated. In such cases, the law of Pakistan should be applied. Qadiyanis are Kafir, and it should be permissible to counter their toxic machinations to spread disinformation but clearly and consistently calling them out as Kafir.
Similarly, valid religious scholars have opined that any Shia who adheres to certain heretic beliefs, such as the non-finality of Prophethood, or non-authenticity of Holy Quran, or the honor of the Mother of Momineen etc., such persons are also Kafir. Religious scholars have also categorized Bohris and Aga Khanis as Kafir. But the most interesting thing is that we don't find ANY of these sects causing ANY sort of friction on PDF. There is the usual sectarian hate spewed by both Sunnis and Shias, but you simply cannot blame them for any blasphemy.
These sects (Shias, Bohris, Aga Khanis) are a shining example of how NOT to cause trouble. Lessons should be learnt by others from their behaviour. And their behaviour provides us a benchmark against which we can measure others. WHY are certain demographics over represented in causing mischief? Of course 'mischief' depends on perspective. For Indians, Pakistanis are over represented in the reprehensible act of referring to excrement etc., while for Pakistanis, Indians are over represented in persistent mention of 'begging bowl', terrorism etc.
Interestingly, one usually doesn't associate Indians with religious blasphemy. Yes, there are notable instances, but it is not the norm. For me personally, I have often criticized Muslim Pakistani members for being 'irreligious', 'secular', and tarnishing the true image of Islam.
Regardless, if we want to have a productive discussion, blasphemy of religion MUST be banned. I would personally go one step forward and say religious discussion should be strictly banned - either completely, or it should be strictly restricted to one particular section, and even then blasphemy MUST NOT be allowed. This is a defence forum, and discussion should take place based on facts, figures, logic, and beliefs/intuition that either arise out of vast experience, or from keen understanding of facts, figures, and logic.
If these rules are adhered to, there is no reason why any one particular demographic should be banned. As someone already said, keep you friends close, and your enemy closer. It is important to gain a perspective of the enemy, and let the enemy act as devil's advocate. Let them force us to present logic, and reasoning, but in such presentation we learn about our own blind spots.
And while we are on the topic of bans, off topic discussions MUST be deleted and persistent offenders MUST be banned. This would go a long way in improving the quality of the forum.