It's only a sin if you're harming yourself , your family or any body else in your environment due to your gambling activities . Religions have mixed up definitions of sins and prohibited deeds that are enlisted in their holly books . That does differ from a religion to another , but i'd prefer believing my own definition that a sin is something that we can apply the right or wrong rule on it and that it's level of danger could affect not only your present , but your future or somebody's else present and future .
correct once that you say. and if in my religion baseball may be done because the gambling is banned in the religion of islam.dan other religions probably also rich so.
Every religion has its books, especially the two most famous ones that are Islam and Christianity. As far as Bible is concerned, people have made amendments in it from time to time but if we talk about Quran, there is nothing in this world that can prove any changing in it since the revelation of this Holy Book. I respect all religions of the world because these all teach us to not love money and stop us from gambling. So, gambling is a sin.