en_tn_condensed/rom/04/18.md

In hope he believed against hope

This idiom means that Abraham trusted God even though it did not seem that he could have a son. Alternate translation: "Even though it seemed impossible for him to have descendants, he believed God" (See: rc://en/ta/man/translate/figs-explicit)

according to what he had been told

You can translate this in an active form. Alternate translation: "just as God said to Abraham" (See: rc://en/ta/man/translate/figs-activepassive)

So will your descendants be

The full promise God gave to Abraham can be made explicit. Alternate translation: "You will have more descendants than you can count" (See: rc://en/ta/man/translate/figs-explicit)