Dear Fanfan,
Mary asked me to answer some of the points in your letter because she would like another viewpoint.
She is answering questions 2 and 6, so I will answer the rest:
1. Is there really only One Almighty God?
When the manned space probe brought pictures back of earth looking like a bluish globe about the size of an orange, it became clear to us that this was our home. The probe did not find a throne in space with a fatherly figure on it. Of course, I don't know if this is anything like your concept of God. However, many people still have something like this in the backs of their minds about God. This concept of God dates back to a time when most people were illiterate, and therefore could not understand abstract concepts. The spirit that animates all things is like it is "breathed from God", but is not God Himself.
Today, we believe that the Creator of the Universe is an "unknowable essence." The human mind cannot ever comprehend the Creator, or God, but that does not mean He or She or It does not exist. Everything shows the imprint of the great thought of a Creator. The same kind of order is found in atoms and in galaxies. Think of It as a life force. That might help. It would be not unlike an electrical current, or radio waves, that you cannot see, and can only hear if you have a proper receiver.
3. Wouldn't we then be close to being like God Himself?
Humankind can not be like the Creator because we cannot create life from nothing at all. But we can know about this great Being through the Spiritual Techers that have come from time to time.
4. Will God stop us when we get too much knowledge, and are too like Him?
God reveals only enough knowledge to suit the development of humanity at that time period, and there is always much more beyond that. Knowledge and creation are infinite. For instance, this is from the most current science available: we can see only as far as light has been able to travel back to us, yet we know that there is much, much more out beyond that, which the Hubble Space Telescope can't convey to us yet, because its light hasn't arrived at the Hubble yet. That doesn't mean that it is in darkness out there where we can't see yet. It is all there, going on forever, and we will see more and more, as its light, travelling at the speed of light has time to arrive. There are so many astonishing scientific discoveries being made at all levels now that show a creation that unified from the greatest to the smallest, with similar patterns repeating in variations. Many scientists are no longer opposing the concept of a single Central Will at work.
We believe that this is the time of maturity of humankind, and that is why there is such an acceleration of human scientific knowledge. A new Teacher from God has released the power for this, as well as the Laws and Teaching that will work for this time. Peace can even now be established, if enough people want it, and pay attention to the ways given.
God does not cause great tragedies. Great tragedies are caused by humans not following the teachings they have been given. For instance, the terrible earthquake in Iran causing twenty thousand people to die, was not caused by God being vengeful, but by man not using construction techniques that are available in this day and age, and should have been used to reconstruct that town that lies in such an earthquake prone zone.
5. Our growing understanding should make us purer, but society is only getting worse.
Growing true religious understanding will be the cause of people becoming less materialistic and more spiritual (pure). It is the excessive advance of civilization and materialism, without the balance of spirituality, that is the cause of inequality of opportunity in the world, and the cause of the wars. Society appears to get worse, because the ills of the world are not treated from a spiritual foundation.
7. If everyone in the world believed in a true and good religion this world wouldn't be needed any more, because everyone would go to heaven anyway, so we might as well go straight there.
I can see why you think that this world would be no longer needed if all people were already good, and could go to heaven right away. The reason we aren't all good is because we are give free will and are not robots. Heaven is a spiritual existence, and not a place in the sky. We are here on earth, and have free will to do with our potential what we wish. In the next world our progress is determined by other standards, and what we do here is what is most important for this stage of our existence. It is to ready us for our next stage of existence, which is not just a reward, but is another level of advancement, with wonderful new experiences and opportunities, but also with tests to meet and things to learn.
This is my understanding of it.
Best wishes, Uncle Ben