How do you use 'agape' in a sentence?

It depends on what you mean by "agape".

Agape (pronounced uh-gay-p) means "open to a large extent". For example, "The person's mouth was agape after a skateboarder landed a very hard trick."

Agape (pronounced a-ga-pay) means "love of humanity" or "impersonal love". For example, "It is through the agape of Christ that Christians seek redemption for their sins."