Is it permissible to abandon an older brother who curses religion and the Divine Being when angry, does not care about prayer, and prefers accumulating wealth over marriage?

It is obligatory to advise the brother who insults Allah and His religion and to remind him of Allah. If he does not respond and insists on this disbelief, then it is legislated, and perhaps even incumbent, to boycott him for the sake of Allah. Scholars have clarified that boycotting a disbeliever or an apostate is obligatory if advice does not benefit them, and that boycotting one whose disbelief has been ruled upon from among the people of innovation is obligatory, unlike the people of the Dhimma and the people of war.