Some people say that Evolution was invented by the Government in order to combat the Church as they were losing control of their people.

Obviously, most people would think this is nonsense. Which is true...
You don't need to have access to the greatest technology in Radiometric dating to date fossils and measure change.
Anyone can access the information needed to prove to themselves that Evolution is real, observable, provable Science.

The word Theory can be used to mean something speculative and tentative. In everyday speech it probably is used in that sense. Scientists often use it in a much more positive sense. The easiest way is to use the ordinary language term, Fact. In the ordinary English sense of the word fact, Evolution is a fact.
The evidence that makes it fact is partly fossil evidence, partly comparative evidence looking at modern species and comparing their bones, organs and their general structures but especially their molecules and genes at a molecular level. This is extremely persuasive and powerful evidence. If you compare the genes of animals and plants you find that the pattern of resemblance is a branching tree and that tree could only be a family tree. Other very persuasive evidence is the geographical distribution of animals and plants on the islands and continents. They are exactly where we should expect them to be.

Natural selection chooses among self-replicating entities. Those self-replicating entities have some kind of power over them being copied and passed on. In practice that almost always means choosing between alternative DNA genes. There is an unequal survival of genes throughout history that is natural selection. Bodies are constructed of genes that have been capable of surviving in the past. They are good at surviving because they are good at constructing machines in which they survive.