Praise be to Allaah.
Firstly:
Not praying is a major sin
and cause of doom; in fact it is kufr according to the more correct of the
two scholarly opinions, as has been explained in the answer to question no.
5208 and
2182.
The kufr of the one who
does not pray leads to numerous rulings in life and after death. Meat
slaughtered by him is not halaal, it is not valid for him to be a wali
(guardian) or witness in case of marriage, and if he dies he is not to be
washed or the prayer offered for him, and he cannot be buried with the
Muslims.
You should carry on calling
him, advising him and reminding him, in the hope that he may repent and come
back to Islam. See the answer to question no.
47425.
Secondly:
The money that he spends on
you is not regarded as haraam or impure, so long as he earns it in a
permissible manner, such as a job or trade and the like. What is meant by
the hadeeth, “Every body that is nourished on haraam, the Fire is more
befitting for it” [narrated by al-Tabaraani and classed as saheeh by
al-Albaani in Saheeh al-Jaami’ (4519)] is wealth that is taken in
haraam ways such as stealing, deceit and so on.
We ask Allaah to guide you
and give you strength, and to guide your father and enable him to repent.
And Allaah knows best.