David Hume did a great job covering this, that you cannot get an opinion from a fact, facts cannot provide goals or preferences, they can only tell you what is true or false, opinions are inherently goal oriented, they are ideas for the best route to reaching a goal or preference. This is the is vs ought dichotomy, and anything you know cannot be used by itself to decide what to do with that knowledge. Same thing with religion or philosophy, which was once in the place where science now resides, in explaining the world and its workings. If you know God and Satan exist, and you know heaven and hell exist, and you know that your soul exists, and you know that following a given set of rules will get you into heaven and keep you from going to hell. Well, without a goal that is all just neutral facts about about way things are, it's only when you desire that you soul would go to heaven and not hell, or hell and not heaven (or anything you'd prefer that makes these details pertinent), that this information is able to be acted on. It is only the presence of a goal or preference that leads you to use what you know to make decisions. The good part is that you cannot avoid having goals or preferences, it is seemingly unavoidable while your brain is functioning, so you will never lack a standard for making judgements, and never lack a purpose motivating you to take actions and make decisions. The important thing when making moral decisions I to start by asking yourself what it is that you want, and what do you no want, then make your morals so that they conforn to both of these, pursuing the former while avoiding the latter. Without knowing what it is that you desire from your actions, you have no standard to evaluate your actions against, and you are morally lost. Falling into slave morality, or worse, the abyss. If it feel weird that you are essentially adopting your own moral code it shouldn't, an impersonal morality is inhuman and leads to terrible places, your morality should be your own, it should be personal, because it is something of the human nature.