What is the ruling on a father who does not pray and does not acknowledge its obligation, curses some of the Companions, speaks ill of Lady Aisha and the righteous, casts doubt on hadiths, shows bias towards the Shiites, mistreats his family, and prevents his children from religious observance, and how should he be dealt with?

Your father is considered an infidel (kafir) and outside the fold of Islam for several reasons:

He denies the obligatory nature of prayer, which constitutes apostasy by consensus. Even if he were to neglect it out of laziness, he would still be considered an infidel according to the soundest opinion. His cursing of the Companions and his adherence to the Raafidite (Shi'a) doctrine, which deems most of them apostates. This is disbelief (kufr) because it is a denial of Allah and His Messenger in their praise of them, and it is an assault on the Sharia, on the Prophet, and on the Divine Essence. His slandering of the Mother of the Believers, Aisha (may Allah be pleased with her), which is disbelief and apostasy.

How to deal with him:

1. You must disavow his beliefs, statements, and actions. 2. Invite him gently using various methods, such as debates, audio recordings, and books. 3. Be careful that he does not influence your mother and siblings. 4. Defend yourself with good character. 5. Do not despair of his guidance, and continue to invite him directly or through Sunni scholars he trusts. 6. Supplicate for him frequently during virtuous times.

If he repents, he is your brother in faith. If he persists, you must restrain him, and if you are unable to do more, then denounce his actions in your heart.