User blog comment:LastationLover5000/Gods or Spirits/@comment-6743632-20130717133159

not necessarily, that is only if you look from the view of Japanese,  gods may be from dozens of mythology, only Japanese Gods are known as Kami, But, In Greek Mythology or Celtic Mythology or any others, they are simply refered as Gods and Deities. In fact, in Chinese Culture, Siddharta Gautama may not be a God from his lifetime, but his existence may be close to one, he rejects the existence of a God, but he awakened himself and reached a higher realm of existence

Furthermore, there may also be Gods from the past(which haven't been clearly explained yet), but they might had disappeared from our daily lives, due to humans losing faith and beliefs in them(this is just my hypothesis anyway). Remember, Gods in mythology are not invincible, they may be immortal or possess Longevity, but they can be killed. But you are also right, the Gods in Fairy Tail, may be refering to spirits as well, Gods are also a type of spirit, a divine spirit, that is. They may even be spirits which possess powers close to a god, hence the name God Slayer magic