Proof that I'm immortal

[Shantideva]

We're just a part of things, not above them, no matter how intelligent we are. We live in a cycle of life and death like anything else in nature. Nothing separates us from our surroundings other than our ego, which is an incredible thing but also tends to curse us into holding a massive misunderstanding of the world around us, which generally results in religious belief and superstitions. 

I would not say that we are immortal though. When thinking of ourselves purely in terms of energy, you're right. It's healthy to think about that sometimes, for the reasons mentioned above. The ego is what creates our identity. Obviously, that ceases to exist upon death. I'd argue that, while we are not immortal,  we experience immortality... if you make the assumption, as the majority of us here do, that you cease to exist upon death. We know we're not immortal because we see death happen in real time, but we will never truly experience our own death. Let's hope the dying part isn't too bad though...

Then what of "ego death?"