Hmmm. Churches in France do seem to be suffering a terrible run of luck lately.

[Burney]

Well since the Paris Fire Authority have already said they don't believe it is Arson, unless you are assuming they are lying to protect some group, then i would suggest it was an accident is a very high probability

Not quite. “There is no indication that this was a deliberate act,” is what's been said. Absence of evidence is not evidence of absence.

Here's something that never happens in normal fire investigations: people ruling out arson while the thing's still smoking.