As tragic and misguided as this attack is, none of the people commenting seem to notice or understand that these attacks are political, not religious,even if the attackers are usually Muslims. Russia is at war with ISIS. They are bombing them in Syria. That's a fact, not an opinion.  
ISIS unfortunately responds by attacking civilians. Of course it's not right, but it's the reason for the attacks. To blame it on religion is simple-minded. One and a half billion Muslims are not bombing anyone. If the attacks were about religion, the world would be a much more dangerous place. 
If you think I'm wrong tell me why.