Mark 9:23

The exchange around this line is the reason it is worth reading carefully.

A father has brought his son to the disciples and they could not help. He then says to Jesus: if you can do anything, have compassion on us and help us. Jesus picks up his own phrase and hands it back — if you can.

What happens next is the most honest sentence any parent in the Gospels says. The father cries out: I believe; help my unbelief.

That is a self-contradiction and Jesus does not correct it. He heals the boy. Which tells you something the verse alone does not: the faith being described is not a state of unmixed conviction. This man had just declared his belief and his unbelief in the same breath, and it was sufficient.

The grammar of Jesus' reply is debated — whether the emphasis falls on if you can or on all things are possible. Either way the conversation moves the question from what Jesus is able to do to what the father is willing to bring, and what he brings is a divided mind and says so.

And the disciples ask afterwards why they failed. The answer given is not that they lacked technique. It is that this kind comes out only by prayer.