I'm new here, too, but I felt moved to reply. My condolences to you and your family. It sounds like some hard times, indeed. Dealing with religion's effect on these things can be difficult in the best of times.
The reason that your father and the rest of the family have turned so firmly to religion is that they are afraid and desperate. Religion offers them both comfort and the hope of divine intervention. There is nothing you can do but let them pray, unfortunately. However! When it comes to medical attention, I would suggest standing firm. Play into their beliefs if you must. Tell them that perhaps the medical specialist/treatment is the manner in which God is helping. Whatever it takes to get proper medical treatment for your father.
But leave them to their religion. It gives them comfort and hope. Right now, an attempted de-conversion could do more harm than good.
That's my gut reaction, at any rate.
The reason that your father and the rest of the family have turned so firmly to religion is that they are afraid and desperate. Religion offers them both comfort and the hope of divine intervention. There is nothing you can do but let them pray, unfortunately. However! When it comes to medical attention, I would suggest standing firm. Play into their beliefs if you must. Tell them that perhaps the medical specialist/treatment is the manner in which God is helping. Whatever it takes to get proper medical treatment for your father.
But leave them to their religion. It gives them comfort and hope. Right now, an attempted de-conversion could do more harm than good.
That's my gut reaction, at any rate.