It doesn't take a great deal of effort to get the facts about the Syrian civil war. [...]
It takes even less effort to see how opportunists with common interests in the region have seized on historical Islamist divisions to foment internal strife in a country with a relatively good record in terms of security.
True, there are various Muslim sects that hate each other, but it's equally true that there are non-Muslim dirtbags using that truth to mask their own hate-filled and greed-driven activities in Syria.
It seems you're looking to invent conspiracy theories where none exist. There is a lot of consensus that the internecine slug-fest in Syria is an extension of what is happening in Iraq. Iran has an interest in making alliances with the majority shia population in Iraq. Iran also has a presence in Lebanon via their proxy army: "Hizzbollocks". The shia have taken sides with Assad and this has caused Arab jihadists to enter Syria as 'rebel" forces.
Do some research and you will discover pretty quickly the angst being felt by the KSA and neighboring Arab states regarding the Persian (Shia), foothold through Iraq and into Syria.