All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
We have already clarified in Fatwa 184083 that whoever has committed a sin for which there is no Hadd (prescribed punishment) and no expiation, then the punishment is Ta’zeer, which is a discretionary punishment (which is not determined in the Islamic law), so please refer to it.
Dear sister, when debating with non-Muslims, we advise you to discuss the principles of Islam before discussing subsidiary issues, because the wisdom behind some Islamic laws may be obscure to some people and it could take some time to debate about it. Calling to Tawheed (the Oneness of Allaah) and the principle of Faith is the foundation, and all other matters are subsidiary. For more benefit, please refer to Fataawa 20859 and 129867.
Allaah Knows best.