He works for a company that sells CDs of Qur’aan and hadeeth, and also CDs of music and movies

If you can make your work dealing only with the CDs of
Qur’aan, hadeeth and similar material that is beneficial or permissible,
and not deal with anything that is haraam, then there is nothing wrong
with you staying with this company. 

But if that is not possible, in that the one who works at
this company has to work in all sections and he cannot limit it to some of
them, then it is not permissible to work in this company, because that is
helping in sin and transgression, and spreading evil and haraam things, and
Allah says (interpretation of the meaning):

“Help you one another in Al‑Birr and At‑Taqwa (virtue,
righteousness and piety); but do not help one another in sin and
transgression”

[al-Maa’idah 5:2].

The scholars of the Standing Committee for Issuing Fatwas
said: 

It is not permissible for a Muslim to help anyone in that
which involves sin, disobedience and transgressing the sacred limits of
Allah. End quote. 

Fataawa al-Lajnah al-Daa’imah,
13/173 

The scholars of the Standing Committee for Issuing Fatwas
were asked: 

I own a shop that records cassette tapes and repairs radios
and televisions. I rerecord these tapes to sell them, wholesale and retail;
these tapes contain both good and bad material, and some of them contain
songs and nasheeds, and Qur’aan, and religious lessons. I am a man with
dependents and a family, and my eyesight is weak, which makes me rely on
earning my living by selling these tapes despite what they contain, more
than repairing radios and TVs, because there is not much of this work. I am
a religiously committed man and I am worried about the provision of my
family. What is the ruling? 

They replied: 

It is not permissible for you to record songs and music and
the like, or to buy and sell such things, even if you do not listen to what
is recorded on it, because this work of yours is helping those who use them
for the purposes of sin and transgression. And Allah says (interpretation of
the meaning):

“Help you one another in Al‑Birr and At‑Taqwa (virtue,
righteousness and piety); but do not help one another in sin and
transgression”

[al-Maa’idah 5:2]. End quote. 

Fataawa al-Lajnah al-Daa’imah,
26/274-275 

The money that you have learned from this work is mixed; some
of it is haraam and some of it is halaal, but the portion that is haraam is
greater if the haraam activities of the company are greater. 

Our advice to you is to leave this company and to think
positively of Allah. Whoever gives up something for the sake of Allah, Allah
will compensate him with something better than it, and whoever fears Allah,
He will make a way for him to get out (from every difficulty) and He will
provide him from (sources) he never could imagine. 

And Allah knows best. 

For more information please see the answer to question no.
98062.