I don't follow any particular religion, but I'll go by the all-powerful assumptions of what most book-based religions teach:
- What we perceive about God or gods, is false or warped; Glorified to make the said entity bigger and better than he/she/it is. This still happens in this day and age.
- God only exists during life not death. Therefore, when you die, so does your god. Granted that doesn't imply absolute death but more in the sense of when you die, time stops because time is a constant in life (excluding universal masses that may warp space-time). Just replace time with God and presto.
- Omniscient/Omnipotent could be interpreted in the way that he/she/it is to us. I.e. Humans can never or will never be able to kill a divinity, nonetheless, when you have absolute power, you must also have the ability to destroy yourself or an equally divine power.
- Lastly, perhaps more far fetched: "Let's kill love." - Something impossible, or near-impossible. Concepts, ideals, legends etc. may exist only when acknowledged. That doesn't mean that they must be believed in, as rejection of them equally validates them. So maybe when the ideal is lost to time, which may never happen for humanity but is theoretically possible though the chance is minuscule, then god(s) die. In this case, humanity can kill a god.