im putting to you the dilemma of basing interactions with other people only on 'do unto to others as they would do to you' basis when those people may not be in a situation to 'do unto to you', either at that moment or after.
Because morals aren't about a particular moment, they are about how you live your entire life and again, though I feel like I am banging my head against a brick wall, are nothing to do with religion. People are nice to each other because they want other people to be nice to them, and are kind to vulnerable members of society because they know that they might one day be a vulnerable member of society. I don't understand why you are struggling to understand this basic concept?
so your daughter would pay back to you what you did for your grandmother.
Ah, it becomes clearer. You think moral behaviour is 'pay back'. Well, I disagree. Moral behaviour is not about pay back or even pay forward, it's about making life pleasant for everyone.
but what if, in caring for you, your daughter cannot lead a life of uninhibited self fulfillment? what if she doesnt want to? what if she sees it as a burden? should she feel guilt at feeling that? should she do it even if she doesnt want to because its expected? part of being a dutiful child? now you make up your own moral position but why should your daughter take it?
I don't expect my daughter to give up her life to care for an elderly mother. It might not be my daughter, it might be someone else's son or daughter doing the care, but I would hope that they were also raised to treat others with kindness and compassion. Again, neither of those things rely on religion, especially not the religion of the God of Abraham.
It would be very easy at this point to find lots of instances of extremely religious people, of all persuasions, carrying out acts of violence and anger against others. Of course, the religious will say "they are not carrying out the rules of their God when they do this", but the person who is carrying out the violence is utterly, utterly convinced that their God's rules allow them to carry out the violence and anger. Who are you or I to say that they are wrong if their God is telling them it is okay to behave in that way?
As I said upthread, I am not an atheist, but have no problem with those who are - I've met some surprisingly spiritual atheists. I suspect we're just built differently, and an omnipotent Divinity should not be limited by human concepts such as existence/non existence. I do have a huge problem with those who think that morals and religion are linked, or who pussy foot around those areas of religious writing which are deeply offensive to non-members of that religion, such as the suggestion that anyone who doesn't accept Jesus as THE saviour is going to hell.
I left the Interfaith Network I was part of when I realised that the two people at opposite me were convinced, to the very core of their smug beings, that everybody else around the table was going to eternal pain and suffering. I found that a very amoralistic viewpoint.