I think this is related to
The Seven Deadly Sins
I am the reasons why you burn
well after your left in the end of your turn
Taking "burn" literally, these actions will send you to Hell. The end of your turn meaning once you are dead.
a plethora of actions lead you here
under a septenary of hate and fear
There are many reasons (a plethora of actions) one might commit any of these transgressions, but most of the time hate and/or fear are involved, as any good Jedi would tell you. In addition, septenary directly links to seven.
Situated here, desolate of fortitude
just molded eyes and tunnels of fued
"Desolate of fortitude" means you are lacking resilience, and cannot stop yourself from committing them. Molded eyes and tunnels of feud sounds like some depictions of Hell from the Renaissance era to me.
for an act of me is negligible advice
I wouldn't advise someone to commit these acts.
my existance defended by who surmise
The existence of "sin" at all is defended by religion, which is literally people who surmise (suppose something to be true without confirming evidence).
In addition, the title has a capital S at beginning at end instead of the usual title case:
Safety in numberS, so the answer could be shortened to