How can I guide my father to repentance and faith, when he is severely distant from religion and does not accept advice? And does the noble verse: (Indeed, you do not guide whom you like, but Allah guides whom He wills. And He is most knowing of the [rightly] guided) mean that I should stop trying to guide him?

If the father abandons prayer, he is in grave danger, yet this does not negate the child's duty of piety towards him. Allah has commanded showing piety to the disbelieving parent, and the greatest act of piety towards him is striving for his guidance, by supplicating for him and softening his heart. Advice is required as long as its benefit is hoped for, and it can be indirect. The guidance sought from the servant is the guidance of indication and instruction.