Study is necessary to know and follow the laws.
Circumcision today is based on religious reasons (Judaism and Islam) and medical reasons (like if you can't pull it back and clean). There are no other reasons to do it but only in the US is it done routinely for appearance.
Pipe smoking is not dictated by Judaism. If a man wants to smoke a pipe, he can do so for non-religious reasons.
It is only important to those who believe in a religion. The reasons they find it important varies. As do the religions.
the Inca calendar was important for religious reasons
The only "important" reason is the religious one but there aren't really any reason to circumcise unless it's for medical reasons.
Other European countries were torn by religious and political conflicts.
Other European countries were torn by religious and political conflicts.
Jamestown was primarily established for economic reasons, not religious reasons.
Assassination is the murder of someone for political or religious reasons, so you don't really have to be important, you just have to be seen as a political or religious threat by some idiot with a knife/gun/bomb/whatever.
For exactly the same reasons that people who hold religious beliefs today think their god is important
It was more for political and social reasons, than for religious reasons.
The reasons usually given are pity and sympathy - not moral or religious reasons.