How does one return the salam to a disbeliever if he greets a Muslim?

Question:
I ask Allah for you, Your Eminence, father. The questioner says: If a disbeliever greets a Muslim by saying, "As-salamu alaykum wa rahmatullah," how do we respond to him?

Answer:
Return the salam in general terms. If he says, "As-salamu alaykum," you say, "Wa alaykum as-salam." If you say, "Wa alaykum as-salam wa rahmatullah," that is better. If you say, "Wa alaykum as-salam wa rahmatullah wa barakatuh," that is better and better.