What is the ruling on dealing with an elderly, poor person who uses qat and suffers from psychological problems that sometimes drive him to curse the religion and the Lord, then he repents and seeks forgiveness, and is it permissible to give him charity in this case?

You must advise this man to stop using qat and to repent from insulting religion and the Lord. Insulting religion, while of sound mind, is an apostasy from Islam. As for his praying alone at home despite being able to pray in congregation, he is sinful. If he fulfills the pillars of prayer, his obligation is discharged; otherwise, it is not. Giving him charity is permissible as a gesture of maintaining kinship ties. His religious welfare should be considered. If the charity inclines his heart and draws him towards the truth, then it is preferable. Otherwise, withholding it is preferable to deter him. The deciding factor in this is the prevailing assumption.