Not a believer, but a practitioner. I believe if I do the right thing I will be a better person, and happier, even if golden coins don't exactly shower down each time.
On the other hand, many of the terrible things that occured in my family were just completely random things by chance, and much of it was 'good people that bad things happen to' and could be viewed as 'senseless tragedies'.
In the general idea that people who do good things have a better life - usually, but not always. In the general idea that bad people eventually get to suffer for what they do, again, usually it seems to work out that way but not always. I think some events are rather random, and I don't think bad people always get recompense. I think 'bad things happen to good people'. Just read a real interesting book by Bart Erhman who explains how the Bible addresses the problem of suffering. Sometimes in the Bible suffering is a punishment from God for sins (frequent in Old Testament), sometimes it is bad things happening to good people, sometimes good people suffer because of what bad people do, basically is how it appears in the Bible.
And I do think that innocent people often suffer for the wrong actions of others. For example, a woman I know who is fairly successful in business in a small way, who is a cheat and liar, put a great deal of pressure on one of her kids to be in the same business and in many ways, to be like her. Even at the age of 7, the kid wound up in a position of trying not to get in trouble by being truthful with customers about what work the mother was not doing. So one of her kids is very depressed, unhappy, directionless. The other seems very happy but was more or less ignored by the mother. I'm a little puzzled by the problem of suffering myself, and why innocent people suffer for the dishonesty or cruelty of others. For example, an abuser who targets a small child who has never done anything wrong.
"Hindus believe in reincarnation". Some do - many younger Hindus, or those who believe in various non-traditional ideas, today do not. It might better be said that 'in the past, reincarnation was a common belief among Hindus'.
There are just as many different beliefs in Hinduism as there are different groups in Christianity, well perhaps more. Some groups are completely monotheistic, some claim the various gods are simply 'avatars' (a form of God that represents what people need).
'Christianity influenced other religions'. Hinduism predated Christianity by at least 2000 years, probably much more. There's just as much evidence that Hinduism influenced other religions. There are many who suggest Jesus (rather than just his disciples) traveled to India and influenced as well as were influenced by Hinduism. My own feeling is that there is a complex two way action, and constant exchange, between most religions, including back and forth between Christianity and all the other major religions of the world.
People who study world religions comparatively, often will suggest that most religions evolve and change together, often in much the same way and in the same order.
'Karma is the rule that what you do comes back to affect you'.
Karma is like that in various Western New Age groups who THINK they understand Hindu Karma and who also THINK they are doing and believing what Hindus follow. They aren't, at least not in more traditional Hinduism.
In Hinduism, at least traditionally, Karma was a part of a complex system of levels of society. Karma suggested a reason for why some people are born poor, limited and regarded as a low form of person. A person's actions in previous incarnations.
Sounds fatalistic? Well there is a flip side to it. As one very disadvantaged person told me, no one actually for a fact knows the will of God, so no one really can say 'I can't try this new thing, or go to school, because that's not my karma'. No one actually really knows what their karma is (they don't remember what they were in a previous life), so all they can do is work hard just do the right thing.