My question includes two parts. Firstly, I would like to know whether it is justified to have the division of countries with respect to religion. Secondly, I have heard that in some countries people follow "no religion". Isn't there any way to give this freedom to each and everyone of this world, to follow "no religion"?
My answer to your very rich and complex question is that religious freedom is not given, it is historically constructed, and in singular ways.
There are countries on which it is relatively easy for people to be unaffiliated to any religious denomination, and to publicly manifest themselves this way. This is a distinct feature of modern cultures, where the effective separation of state and religious traditions has been institutionalized, and republican traditions are strong.
In some others, what happens is that the dominant religion has become more and more tolerant towards how its members treat their private life, and mitigated in the ways it disciplines public conduct, creating what can be viewed as de facto religious freedom. Historically, this has been more frequently the result of the ascension to power of empires that dominates over large regions, constituting multinational and/or multiethnical societies.
These two situations are not the necessary outcome of a deterministic process. Social and political expressions of religion are very dynamic. In a broad sense, and as far as we know, religion is a strong human impulse, pervasive in all cultures and times. Although we can all lean towards the defense of religious freedom as an ethical proposition, is it possible to have a society where religious practice is never strongly binding, and where to be or not affiliate is always a decision taken lightly and playfully? Is it desirable?
The jury is out on these, and other questions. The debate continues.