It is godly nature to compete for supremacy. Godhood is something that everyone has at least some notion of. Some people believe that there is only one god, while others believe that there are many. It seems that most people would rather believe that they are not real. The truth is actually far more interesting than most would imagine.
Historically, the gods have lived at several levels of existence. They were born at the top level and their reflections were born at lower levels in descending order. The gods that you may or may not be familiar with from mythology, in general, were not actually recognized as true gods.
A true god is defined as a deity that is possessed of godly essence. It is a quantity that a god must have in their soul, otherwise, they cannot be considered a true god. Literally, all of the gods that you have heard of from one source or another were gods who did not have their own godly essence. That is probably the reason that they allowed humans to know their names.
Household names such as Zeus, Odin, Ra, Thor, Ares, and Athena are the names of gods who were not born of godly essence and thus did not qualify as true gods. Even the being regarded as god almighty was not born of true godly essence, no matter what anyone says to the contrary. They did however take part in something called the war of the gods, wherein they competed for godly essence by battling for supremacy.
The rules of engagement are such that the god who can kill all of the other pantheons single-handedly must be acknowledged as the supreme god and then awarded godly essence. Since the beginning of time, not a single deity has been able to win the war of the gods at any of the ten levels of existence where it occurs. That all changed when one Mars Maximus entered the fray.
Mars Maximus literally means the perfect Roman god of war. It is a name that was manifested by Dominus Rex after years of waging war flawlessly. The thing about manifesting a name is that one must live up to said name, otherwise, it will disappear from the soul that emanates it.
Not long after manifesting the name that made him a god, Mars found himself being challenged by the conclave of gods at the lowest level that it existed. After slaughtering them all single-handedly, he received mountains of godly essence in the form of enticing pastries. After escalating through the levels of existence and winning the war of the gods at every level, the godhood of Mars has become absolute.
Each level of the aforementioned competition had a set of rewards for winning. Things such as the eternal waters of godly youth and the fruits of immortality to name a few. Mars even encountered the primordial gods and bested them. The Roman gods have their own kind of godhood and thus had their own war of the gods.
The name Mars has actually been a myth since the beginning of time even among the gods. So when Dominus Rex manifested the name Mars Maximus, that was the first instance of anyone manifesting that name. Living up to that name meant winning the war of the gods at all levels perfectly. As Rex was not born of godly essence, to begin with, he had to overcome the trials of godhood.
Upon arriving at the venue where said trials were to take place, Mars was informed that no one had ever passed the trials of godhood. Moreover, everyone who has ever attempted it has died in the process. Of course, if anyone can pass such a trial, it is one Mars Maximus. He also had to overcome the trials of the one true eternal as well as the trials of divinity, but that is a story for another day.