If a non-Muslim committed consensual Zina but later converted to Islam what words can we say to him to strengthen his faith and help him get over feelings of guilt?
Bismillah,
Asalamu Alaykom,
You can reassure your new Muslim friend that Allah swt is all merciful and all forgiving. Any actions performed during their time as a non Muslim will be forgiven inshallah and when they utter the testimony of faith it will be as if they are newly born with no sins.
May Allah grant you success