Fatwa ID: 04933
Answered by: Maulana Abrarul H. Hasib
Salam, my friend has a baking business and she was wondering if it’s halal to make cakes for people that will use it for haram purposes, for example, a christening ceremony, or a haram wedding
In the name of Allah, the Most Gracious, the Most Merciful
It is appropriate and best to refrain from baking such cakes, as this will be aiding to Haram acts and their Haram customs. Although the income from this would be Halal. 
Allah Ta’ala says: “And do not assist each other in sin and transgression (oppression and injustices).” 
You may bake other Halal cakes and you will be saved from any type of doubts in your earnings.
Only Allah knows best
Written by Maulana Abrarul H. Hasib
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
 Durr Mukhtar, Vol 6, Pg. 55, Darul Fikr.
 Tafseel Al-Kalaam Fi Mas’alatil I’anati Alal Haram, Pg. 12.
 Surah Maa’idah v.2