There is no actual evidence for god whatever any believer says.
There isn't, which is why they are believers. You need to believe, you cannot "know". Even if some religious people do say they know.
And if there really was one, what sort of a god is he to play with us the way he does?" (Not a nice one!)
Only if you think that god is manipulating events.
The humans of the world who wish to believe in a higher being, obviously cannot even unite/agree on which 'god' to believe in, and even those who believe in the same god, cannot agree on what he wants from us and how to make him happy. So there will always be multi-opinions/arguments. (And a LOT of room for doubt?!)
Assuming there is a higher being that is god, and that is beyond our comprehension, we can understand or perceive it in different ways. This is moulded by our personal experiences, culture, and also our biology with its limitations. Every single person has their own experience or idea of god (or lack of)
For a rational person, does this not tend to point to the conclusion that it is all imagined/made up/invented by man as a 'crutch'? (As no-one can prove anything?) And that 'god' only exists in each person's imagination? (Like the feeling of love for someone we might have? Just a sort of chemical thing going on and not a universal truth?)
Could be, but then why would we have developed a mechanism to "invent" god?
Although the idea of a god, or gods, may stem from our need to control things. That we can address that god and have a result in our benefit. (thinking out loud)
Even if there was a 'god', why or why would we need to 'worship' him/her or have certain customs which can change dramatically over time as we learn things and see the error of our previous ways? (That's the bit I really fail to understand.)
Religions, the way I see it, and their traditions, rituals and customs, are basically ways of bringing together communities in a common ground and guide people in their quest to understand or be closer to god. Unfortunately, and due to human nature and as many social constructs, it can also divide people. :(
Worship is about practice and learning. As I see it, it's not that different from meditation, but certainly forces us to stop our normal lives and reach out for that something else, but also to make us think about our own lives, how we relate to each other, about our choices.