Batman He Ain't

When the Duke of Milan is brutally murdered, the Assassin Giovanni Auditore is dispatched to investigate. The answers he uncovers implicate Italy's most powerful families reaching all the way back to the Vatican itself.

"Assassin Clan" in 1191, who were on a mission to obtain a "Piece of Eden", an artifact capable of creating illusions, from the Knights Templar. The character of Al Mualim and his clan are based on an Islamic sect known as the Order of the Hashshashin from which the term assassin originates.

Al Mualim is himself a member of the Knights Templar. He denounces religion and other seemingly supernatural events (e.g. the parting of the Red Sea, the Ten Plagues of Egypt and the presence of the Greek Gods in the Trojan War) as illusions caused by it, then states his intention to use the artifact to compel mankind into a brainwashed state and so bring an end to all conflict.

So basically the hero of Assassin's Creed is a secret Muslim running around killing Christian leaders because Christians are evil. Typical liberal tripe. The webseries however is set in a different time period and may weave a tale of how Islam saved Italy or something entirely non-historical unless the assassin tradition was somehow absorbed by the Templars which may be implied by the political setting.

I bet five bucks the assassin was raised Muslim but got away with going to United Trinity for twenty years anyway.