Islamic culture and wisdom deem human deeds to be eternal like his essence, and the source of happiness or unhappiness in the hereafter. Therefore, moral actions, namely, deeds in accordance with the standards of religious (Islamic) morality, will be the source of human happiness in the hereafter. Following the explanation of the two concepts of immortality and union of deeds with human nature, Lady Amin Isfahani, known as the Iranian Mujtahida, has been led to the conclusion that the criterion of moral action is the afterlife happiness of man; happiness whose inherent characteristic is immortality. According to the Holy Koran, the union of moral action and human nature in worldly life is a truth under the veil that will appear in the hereafter. If man believes in the immortality of his essence and consequently his deeds, he will organize all his deeds according to that criterion, namely, immortality, and will act in accordance with religious criteria. Given the reliance of Lady Amin on the culture of the Koranic and Islamic wisdom, this study measured the relationship between human immortality and moral action in an explanatory and analytical manner, and concluded that Lady Amin Isfahani identified human immortality and his actions as a criterion. This criterion is in accordance with the teachings of the Koran and tradition and is superior to other criteria.