Fans have been discussing the various factions of the New World, praising some, while disregarding others. The basis for judgment seems to be the sparse lore given on the factions, which needs to be rectified via a history lesson.
Many feel antipathy towards the "yellow" Covenant faction, as they are perceived by many as religious fanatics and zealots. It is true, that they are presented this way on the official site: "They are a fanatical order that has charged itself with cleansing the land of heretics and defilers so that its true holy nature can flourish and justice can be restored."
At least, that is the information given by New World developers to make this faction distinct. However, New World is heavily drawing its inspiration from actual history, and we can't talk about medieval times without its very close connection to religion and many different groups of faith.
Marauders are inspired by the Portuguese conquistadors, a strictly catholic army that conquered and settled in the New World - South America.
The Syndicate is a mix of many different groups such as nobility, tradesmen, scientists, priests, and many others. The all-seeing eye in their logo is a direct reference to the Bavarian secret society of the Illuminati. Again, the diversity of this group is represented by the famous "plague doctor" featured as a representation of the actual Syndicates because they were physicians, surgeons, barbers, apothecaries, midwives, herbalists, and priests.
The Covenant is almost word for word inspired by the Scottish Christian movement called Covenanters. Even their flag has a yellow cross on the blue field. They are part of the puritan, reformed, protestant, movement that settled in America.
You may know, that people in England called the War of Independence mostly a 'Presbyterian rebellion' because these protestant forces were the catalyst of its start. In-game Covenant armor also bears a clear resemblance to Puritan clothing, it's not just period inspiration.
Of course, more could be said about each of these. What is important is that all of these have something they place their hopes in. Some sort of faith, belief, or plan for the future. Don't just look for the description of each class, but choose them based on whether they suit you, and make your own way. Roleplay the game, make a Syndicate character that finds faith, or a Marauder that betrays his cause. There is a reason this genre of game is an MMORPG, after all.