Six important ideas
1) Humans do not have "souls". The one great central error in human thinking, from which I believe most of our other errors ultimately flow, is the concept that there is some sort of "soul" or "spirit" or "animating force" within a human being, a "ghost in the machine", something supernatural, unfathomable by the normal laws which describe the behavior of matter and energy. No. The mind is the aggregation of the vast system of highly complex operations which the brain performs. Admittedly, exactly how this works is probably the most challenging problem facing modern science and philosophy. We do know that very complex systems can generate "emergent properties", that is, properties qualitatively different from those of their simpler components, but the mammalian brain must surely be by far the most stunning example -- how does the interaction of complex patterns of signals cascading through networks of brain cells generate a mind with free will, self-awareness, and all the other traits which seem to differentiate humans and higher animals from everything else in the universe? We don't know yet, but that is no reason to invoke the supernatural. Humans have always come up with supernatural explanations for phenomena they did not understand, but when they did become capable of understanding those phenomena, it turned out that there was nothing supernatural involved. The same will happen in this case.
2) We are alone in the universe. For over a century, it was the default position of most scientists and other thinkers that the universe held other species at least as intelligent as ourselves, probably a great many of them. People debated whether they would turn out to be benevolent teachers to enlighten us, super-monsters out to enslave us or destroy us, or merely our equal partners in the advancement of a future shared civilization. But as our understanding of the universe and evolution has progressed, and as the total absence of any of the evidence we would expect to see has sunk in, a more sober view has begun to make headway. I highly recommend this book, which first helped me see the light (and which also contains the best and most readable overview of the evolution of life on Earth that I've seen); on a related subject, here is my interpretation of Fermi's paradox.
3) We humans of today are vastly superior -- mentally, physically, and morally -- to our ancestors of just a few centuries ago. Once nutrition, medical knowledge, and so forth began to improve, humans began growing larger, healthier, and more intelligent (especially as education spread). These healthier people produced healthier children, who not only started off advantaged at birth but also grew up in an environment which was continuing to improve. Over generations these effects have been cumulative, and the trend is still accelerating today. More here.
4) Because of #3, there is no sublime wisdom to be found in ancient "holy" texts or traditions. The reason why texts such as the Bible and Koran read like disjointed, befuddled ramblings is that they actually are disjointed, befuddled ramblings -- the work of minds which were probably, by our modern standards, literally subnormal and mentally retarded. They could not think anything like as clearly as we can, and they were totally ignorant of the true origin, and almost totally ignorant of the true nature, of the world and of mankind. This is why, as people like Christopher Hitchens have pointed out, such texts are riddled with contradictions and pathetic logical lapses which are obvious even to children today.
5) We will soon free our species from the ancient scourge of aging and death. This is the most important challenge facing our rapidly-advancing medical technology. The aging process is already fairly well understood; we know how it kills us, and we know in principle what we need to do to stop it. Actually getting there will take a massive investment of resources and brainpower, but the goal is in sight, even if hazy in the distance. More here; see also this site and this one.
6) The Singularity is near. By around 2045 we will have all the necessary technology to achieve the unification of human and machine intelligence, adding all the capabilities of computers (themselves vastly more advanced than the computers of today) to the powers which the human brain already possesses. Human intelligence will be able to increase without limit, even to levels trillions of times what it is today. The technological and cultural achievements which will follow this are as far beyond our present comprehension as the internet, genetic engineering, literature, or philosophy would be beyond the comprehension of a flea. Read this book for the whole story.