What I am asking is whether you think that your religious or non-religious beliefs about God or gods are the ‘reason’ you are happy. I highly doubt that is the reason people are happy, although they might tell themselves that. If that is the reason they were happy they would not need enjoyable foods, alcohol, sex, traveling, etc., in order to be happy, but I think most people do need those things to be happy.
I think love is important for happiness, but it does not have to be love for God or romantic love. It can be love for friends and family. In my case, it is love for my cats and other animals, since I only have online friends and I have no family or romantic interests. Would I be happier if I had a boyfriend or a husband? I don’t know, but that is a moot point, since men do not date women like me who won’t have sex out of wedlock.
I think certain religious people believe we ‘should be happy’ just because we have our religious beliefs. This pertains mostly to Baha’is, but I think it also pertains to Christians. I don’t know what the other religions teach about happiness. I am sick to death of the expectation of Baha’is that I ‘should be happy’ just because I am a Baha’i. These people are clueless about my life situation and they do not care about it. They are like robots, fully indoctrinated by their religious teachings that tell them that we ‘should be happy' because we have God, no matter what life throws our way.
As for Christians, are you happy because you believe you are saved and forgiven by the blood of Jesus, and because you believe that Jesus/God loves you? That might be one reason you are happy but I doubt you would still be happy if you had a very difficult life situation or if you had clinical depression or debilitating anxiety.