If you define good quan atively then it can be tied to empirical evidence. Example: It would be good if I had 200 dollars to pay my electricity bill.
I have 200 dollars
It's good that I have 200 dollars
If you define good based on how you feel about someone's actions, it's like taste - it can be described but not proven. Even if you taste the food I taste, you cannot prove or ever know we have the same response to it. We can, however, prove we ate the same food. Morality too is opinion based. Being as such, it's not based on fact even if facts do help shape it, and even if several people agree on the basic tenets of morality. We agree with what we collectively want for humanity based on rationality and empirical evidence. Killing freely is bad for society. This has be proven empirically. Do unto others as you'd have them do unto you - treat others how you want to be treated (therefore you stand a better chance of being treated well). Teaching that its morally wrong to murder serves to create a "better" society. In this sense, "better" means something different to different people however to each person it means something that serves their personal needs one way or another. The concept is to allow people to live and enjoy their lives because you want to live and enjoy yours. It can be shown empirically that cooperation can help achieve goals. We consider it good when we achieve a goal we have set, we get a feeling of accomplishment. I cannot prove to you that I get that feeling, but you probably get the same feeling so I don't need to prove it to you. We use this concept to teach our children to achieve goals. They achieve a goal, they feel good about it. They don't require proof that our feeling is the exact same as theirs - they experience it. That doesn't mean the feeling isn't a science based phenomena. Our morality can be whittled down to learned response and self preservation. That is science based as well. Sure, in the more nebulous viewpoint, I cannot prove or disprove we see the same colors, but it's not a problem we face to do so. Like morality, we learn what to like based on finite choices and associations. Those are science based concepts.
Religion is a tick behind the ear of philosophy. Because people have the ability and tendency to seek proof, the things that are not falsifiable can quite easily be shoved into the god box. Religion jumped on that and took ownership of it. This is why the god of the gaps concept continues along even today. Being non-falsifiable though doesn't give religion an out since religion makes a positive claim about the physical reality. Religion then has the burden of proof and because the concept is not falsifiable, it's really not worthy of much consideration.
Some might argue we best achieve everything by hastening the apocalypse. This is the problem with granting religion a philosophy degree - it is not satisfied with pondering "what if". Religion wants to tell us "what is". This is why religion is not a viable answer to philosophical questions. It sets itself up time and again for failure by crossing over into the scientific, falsifiable realm.