The discussion seems to be in two places: How do you ban a religion, and should you.
The only way to effectively ban a religion is to outlaw all practice of the religion, including holy buildings, festivals, public speaking, publication of religious material and congregation of its members.
If successfully enforced this would effectively outlaw the religion and have it removed from the public.
Does this do what you want though? Does it destroy the religion or stop its growth?
No, it doesn't.
Numerous religions have been banned throughout history yet still continue to exist in secret and grow.
Christianity was banned not long after its formation and its members continued to practice in secret in caves, and to recruit members. Once the power that banned it lost the control to continue doing so it exploded into the public way of life and never stopped.
Even religious sects failed to be stifled, as with the rise and fall of Protestantism and Catholicism during the European reformations.
And in the modern day banned religious beliefs, such as those of extremists, thrive through the internet and social media and continue to try to recruit and grow, working on an international stage without care for borders.
You can't stop belief and you can't even stop practice or recruitment. All you can do is hide it from the public and leave it unchecked.
As for should we ban religions, I don't believe we should.
Of course there are religious based groups who cause violence and unrest, as well as organisations designed to manipulate followers for the benefit of individual leaders.
And these should be banned and fought.
But banning an entire religion, particularly a world religion is an awful idea. Not only can it infringe on civil rights in a country, but it antagonises an incredible number of people against your country.
It pushes once honest members of that religion who practiced peacefully to join and form extremist groups who now use violence to restore their religion.
And even if repurcussions are small to begin with we already know that banning a religion doesn't destroy it, and it will grow underneath you. It's a fruitless endeavour.