Do not be afraid of those who kill the body but are unable to kill the soul

"Do not be afraid of people. They can kill the body, but they cannot kill the soul"

kill the body

This means to cause physical death. If these words are awkward, they can be translated as "kill you" or "kill people."

"fear God, because he is able to destroy"

the part of a person that can be touched, as opposed to the soul or spirit

the part of a person that cannot be touched and that lives on after the physical body dies

"fear God because he is able"