The question here isn't whether anyone knows everything about something, but whether there is sufficient information to reach a correct conclusion. A huge part of being correct involves adopting the truth of natural law. So it's really not hard to know the correct answer.
The law that can not be repealed is that it takes a living brain to host a sentient mind. That would be the part that only takes a little common sense to figure out. Most folks who've ever experienced fainting, or who've been knocked out for any reason, could pretty well rely on their intuition to arrive at the correct answer here. But, as I said before, the slightest amount of science would help if there's trouble applying common sense. In this case you would want to look into those regions of the brain that are needed to host the conscious mind. And that would begin at the brain stem and reach to at least some regions of the cerebral cortex.
When those regions are destroyed by injury or disease, the mind ceases to exist altogether. That's simply how nature works, and it's not subject to opinion or belief. Nature isn't affected by human belief. It proceeds under laws that are invariant to our hopes and wishes.
Your wish or hope that you will continue to live after you die is fine, as long as you confine that belief to a condition that doesn't overturn the laws of nature. You simply don't get to take your mind with you, Gravage.
If you need some ancillary facts to help you reason this out, consider the mentally ill. Do you suppose a severely retarded person would live on after death as a retarded mind or not? Consider people severely disabled by psychosis, who live in a fog of hallucinations. Do they live on after death in same terror, haunted by the belief that they are covered with insects, or that birds are attacking them, etc.? And the deaf, do they live on deaf or not? (And what is there to hear without any stimulus? Where is there any sound?) I'm sure you're aware that brain injury can produce blindness and deafness. For the same reason, a brain dead person has no capacity to process the stimulus from the optic and auditory pathways. In fact, the pathways are easily shut down simply by falling into a deep sleep. Brain death is even deeper than that. There is not even any minimal activity to regulate the body functions without the assistance of life support.
The question of whether God exists has no bearing on this. That's just an assumption you're making. If you notice, there is no case in which the laws of nature are ever suspended by God. That's just a extrapolation founded on religious belief which requires you to deny reality. Obviously if you're going to accept the existence of God, you're stuck with the problem of why nature never bows to His will or intervention as you require.
As sure as the sun will rise, your mind will cease to exist when your brain stops functioning. You were simply lied to as a child and haven't completely come to grips with it.