Does the anger of a disobedient father, who harms his children and curses the Divine Essence, prevent his son from entering Paradise, and are there any religious directives for such cases?

A son must show piety towards his father, even if the father wrongs him, and avoid anything that provokes his anger. The father can be advised and reminded gently. The son is not harmed by what emanates from the father unless the son is the cause of it. A father's supplication against his children unjustly is impermissible and, God willing, will not harm them. As for a father cursing religion, if he does so consciously, that is an act of disbelief, and he must repent and return to his faith.