Is an ignorant or interpretative father excused who believes that the righteous among Jews and Christians enter Paradise, and is his silence evidence of his repentance, and what must be done regarding him?

As long as the father's error was pointed out to him, and the noble verse was recited to him, and he was convinced, then this is sufficient. It is not a condition for him to be told that his statement is an act of disbelief (kufr), or for him to verbally affirm that it is a statement of disbelief. Rather, it is enough for him to believe in the truth and repent from falsehood. The issue of excuse due to ignorance or misinterpretation is accepted in this era due to the prevalence of ignorance and distortion. A specific individual is not declared a disbeliever unless the conditions for declaring someone a disbeliever are met and the impediments, such as ignorance and misinterpretation, are absent. The questioner is not obligated to re-engage in conversation with his father, but if he does so in an appropriate manner, it would be good to emphasize that Islam is the religion of Allah, and that faith is not valid except through belief in the Qur’an as a divine text and in Prophet Muhammad as the Seal of the Prophets.