Morality... is it a prison or a tool?

Ah, I thought you were only referencing after the Romans Hellenized. Thought, I don't know if that really "proves" much. There are a variety of things it could indicate. Perhaps to the Romans at the time they didn't really care about "religion" as much, and were more interested in what "looks good/feels good". Or perhaps they believed that religion was totally interchangeable. Or perhaps they came to believe that the Greeks really were the "correct" ones. More likely it was a combination of things.
In general though, even though there are plenty of religions that view themselves as interchangeable with others, that hasn't seemed to have precluded them from religiously motivated violence (towards people that disagree with their religion) in their histories. Though that's more of a "people in general" thing than any specific belief, religious or otherwise.

Can you give me an example?

No. I am staunchly opposed to Catholicism for a variety of reasons, one of which is the large focus on aestheticism. While I don't think making pretty things is "bad" per se, I think they focus on doing so way too much. To me, the "beauty" (or, what attracts people) to the "church" should be the people, not the buildings, rituals, etc. And when I say people, I mean how the people act and live. At least, that's what the Bible talks about (quite a lot).
I feel a bit similarly about many "mega churches" in the United States.

According to history, this is essentially true. Beyond just a basis of "what is permissible", the civilizations with moral codes have (typically) survived the longest. Additionally, the civilizations that have done away with, lessened, or otherwise become less "moral", tend to allow "what is permissible" to grow to the point of societal instability. The primary "moral" that typically is left behind first, is the moral/s regarding "selfishness vs selflessness", which Badgergale mentions, sorta.
In my opinion, morality is necessary for a functional and continuously progressing society, while amorality (the lack of morals) is historically harmful to societal progress and functionality.
Thus, I have always chuckled at the idea that "religion needs to be done away with" or "it causes all wars, violence, etc.". This is primarily because I see religion as the easiest source of morals, which I believe are needed for society to function and progress, based on my understanding of history.

Badgergale is, essentially, correct. And gave a rather succinct and accurate description of the "secular" view on morals.

 

Can I like someone's like?

 

Yes and no, I think.

The overall goal of both a legal system and a moral system is a well functioning society - and our legal system is built over a framework of earlier (Christian and instinctive) ethics.

However, it doesn't necessarily have to be ethics based. Something like traffic regulations are built not over a good/evil system but on largely utilitarian goals - ensuring the flow of traffic/minimizing accidents.

Sometimes this approach can conflict with moral ideas. For example, traditional punitive punishment is often shown as less effective than rehabilitation of criminals - but it is still more popular to lock them up because of a sense that they should suffer for causing suffering.

Ultimately though, i kind of agree that a pure outcome based system has the possibility of becoming a bit un-human, that even if it is inefficient that it's best to retain some idea of morality, fuzzy though it is (and perhaps because it is fuzzy) as a human safeguard against mistakes within a pure utilitarian legal system (a second house/chamber of sorts).

 

Don't forget the Muslim that helped found the United States! (I'm being a troll here. But seriously, some people believe that...).

Thankfully not all moral systems want that sort of thing. More and more moral systems are actually asking for a decrease in that sort of thing (like in the Christian community, where more people are starting to pay attention to the later parts of the Bible where Jesus/God specifically tells people NOT to simply make others suffer as punishment for every possible infraction.).

Agreeing we need morals, or that they're helpful in some way, is easy. Deciding on what counts as moral is where it gets tricky. Mostly because that depends on a person's values and premises. For instance, there's the easy example of abortion: Some believe it is more moral to allow it, while others believe it is more moral to disallow it. (Please, PLEASE don't get into an argument over the morality of it, it's just an example of conflicting "moral" standpoints).