As a matter of fact I would contend that religious instruction would be necessary to balance the slant that students are always going to get from their teachers.
What slant would that be?
Would it be something like this?
We have all this evidence that evolution occurred: here it is.
We have no evidence as to why it occurred, and we also have very scanty evidence about how life originated in the first place.
As regards God, we don't know one way or the other.
Is that the "slant"?
I call it telling the truth.