I would like to work as a librarian but depending on where I work this job includes helping people with research that does not agree with islam (Shirk Mythology) and lending books that they have chosen to people (Some libraries have Grimoires (Books on magical invocations)). I would also have to increase my own Knowledge in alot of areas so I can be an asset as a researcher.. (Such as different religions) What are my limits in Islam to working in such a field?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

It is not permissible for laymen to read the books of misguidance and deviation or books of false beliefs; Al-Buhooti stated: “It is not permissible to read the books of the People of the Book, according to a statement of Imaam Ahmad, because the Prophet became angry when he saw that ‘Umar had a copy of the Torah, and he said to him: 'Are you in doubt, O Ibn Al-Khattaab?...' Also, it is not permissible to read the books of innovators or books that contain both truth and falsehood, and it is not permissible to narrate them as there is potential harm of corrupting the beliefs of others.” [Kashshaaf Al-Qinaa’]

Therefore, if in this job you are not able to avoid enabling laymen and those who have corrupt goals from reading such books, and you provide such books to whoever asks for them, without distinguishing between laymen and others, then it is not permissible for you to do this job, as by reading them, people may be led astray, and you would be helping and cooperating with them in sin. Allaah says (what means): {And cooperate in righteousness and piety, but do not cooperate in sin and aggression. And fear Allaah; indeed, Allaah is severe in penalty.} [Quran 5:2]

Allaah Knows best.