Ruling on teaching in a Christian school

The shar’i ruling differs
depending on the state of the school referred to in the question. 

1.

If it is a religious
school, in the sense that it was established to produce priests, monks and
nuns, and it is working to establish a new generation of this class of
people, then we do not think that you should work there, and we can only
advise you to be cautious and to keep away from it, even if you are being
called to teach other, secular subjects, because by taking part in working
with them you will become part of their institution, and it is as if you are
helping them in their kufr which they want to teach to the children. 

2.

But if it is an ordinary
government school, but has a Christian administration that wants to teach
the Bible, and it is limited to that, then in that case there is nothing
wrong with you working there and becoming part of the faculty, so long as
you adhere to the commands of Allaah and observe proper Islamic hijab, and
perform all acts of worship on time, and have a good attitude and treat
others well, and avoid forbidden things, one of the most serious of which is
loving the kuffaar, feeling comfortable with them and imitating them.  

When working with them, you
should be keen to spread the truth and call people to it, and rid whoever
you can of the darkness of ignorance and shirk. But if the school requires
you to do any Christian acts of worship or traditions, or it is mixed (men
and women together), or you fear that you may be dazzled by specious
arguments as the result of mixing with the Christians, then in that case it
is not permissible for you to work there, and you should not continue to do
so, rather you must leave and shun it for the sake of your religious
commitment and so as to protect yourself from falling into the traps that
the shaytaan sets for the sons of Adam. 

Allaah says (interpretation
of the meaning): 

“O you who believe!
Follow not the footsteps of Shaytaan (Satan). And whosoever follows the
footsteps of Shaytaan (Satan), then, verily, he commands Al‑Fahsha’ [i.e. to
commit indecency (illegal sexual intercourse)], and Al‑Munkar [disbelief and
polytheism (i.e. to do evil and wicked deeds; and to speak or to do what is
forbidden in Islam)]. And had it not been for the Grace of Allaah and His
Mercy on you, not one of you would ever have been pure from sins. But Allaah
purifies (guides to Islam) whom He wills, and Allaah is All‑Hearer,
All‑Knower”

[al-Noor 24:21]

We should not forget to
point out here the danger of these schools when they are opened in Muslim
countries; in that case they are a tool of colonization by stealth, and an
obvious means of corruption, concerning which many fatwas have been issued
by scholars and academic institutions from the time when they were first
established. 

And Allaah knows best.