How can one help a friend whose faith has transformed from Islam to Christianity, and then to a loss of faith in any religion, due to doubts that arose during his stay in the West, and who now compares the Prophetic hadiths with modern scientific data, and believes that Muslims believe without reflection, which has affected his commitment to worship and made him indifferent to God's punishment?

Residing in non-Muslim lands is not permissible except for one who can observe the rituals of his religion and is safe from temptation. This might be the reason for your friend's atheism. To help him return to his religion, consult books that discuss the doubts raised by atheists and engage him in dialogue, seeking Allah's help and increasing your supplications for his guidance. Refer to Fatwas numbered: 134027, 93695, and 145098 for further references.

On the other hand, address the topic of the merits of Islamic Law, utilizing Fatwa (definition) number: 128948. Also, read the book (Usul ad-Da'wah) by Dr. Abd al-Karim Zaidan, which presents Islam as a creed, a law, and ethics.