The issue of Sin

[Leonardo17]

Is that...like..a law of the cosmos that god has to follow..Neo?  There can be only one!

.....is that what happened to all the other gods.......?

If you are using a plural form, In Hinduism these “Devas” and “Devis” (Gods and Goddesses) are to be seen as the aspects of the one true reality. So (maybe) it is more simple for them to direct their prayers to that specific deity according to their needs. They also work as concepts. It probably makes it easier for them to have discussions on spiritual issues.
If you are talking about The Deity and mystical terms, that Being is also thought to be our true essence that is omnipresent in each mean at deeper levels beyond our superficial Ego-personalities (Or at least this is how the issue is being described in almost all mystical traditions). So re-establishing that connection with our true self is important because it’s something that will help us to function in a much better way in this moment in this lifetime. (Again, this is how the issue is being described in many mystical traditions).
Neo-Scholastic:
   There are some theories that come from some prominent Indian Yogi’s that say that mankind is experiencing a certain shift in consciousness since the end of the 17th and the beginning of the 20th century. Old values and old ways of seeing things (especially in spiritual issues) are shifting. Things like Yoga or tai-chi for instance is no longer seen as a form of paganism but is being now taught in some primary schools and universities. We, the people of my generation, have a different way of seing and doing things. We speak several languages, we have access to the internet, we read a lot, we follow discussions on Youtube and Spotify (and more similar technologies are yet to come. Perhaps in the future, books will be free of charge and anyone will be able to read anything freely with an app on their smartphones). In ancient times people didn’t even leave their villages. Books were terribly expensive and were the luxury of some few wealthy and powerful people. There was no museum, concerts and theatre plays were for the aristocrats, Art and paintings were for the wealthiest people. In fact the overall understanding of life was of a brief physical existence that was likely to end in 30 years or so before dying of war or disease. And the afterlife was seen as a physical place (just do the research on this subject) were you would have food, women, gold etc. for eternity (What a madness by the way).
   Today we talk about non-material concepts in spirituality. To dogmatic religions even this is a blasphemy. Dogmatic persons would tell you that I am committing blasphemy as soon as I would start describing what is my vision of heaven and hell. In fact, some 30/40 years ago (people told me) there were even preachers in mosques who claimed that the Americans were lying when they claimed to have descended on the moon since the moon was made of the light of God (“Nur” in Arabic) and it was therefore impossible to land on it. I think you see what my point is
   So my theory is that this is going to gradually change during this century. The mechanic repetition of some rituals and the unconscious reading of some religious material is simply useless. This century’s men and women need more than this. So I believe that the percentage of what I call “consciously spiritual persons” is going to gradually increase. But dogmatism and even fanaticism will still be present. But, as I said, there will be a tipping point in which this is not going to be the norm anymore. I thing that toward the end of the 21st century, we will be at least 40 % and at some point, they will become the minority.