Please help with this C.S Lewis quote

[Warrior 4 Jesus]

Hi everyone,

Warrior 4 Jesus here.
My pastor is conducting a series of church services on C.S Lewis, his faith, the Bible and the Narnia Chronicles in the next three weeks. He sent me some questions, because I offered to help him and I answered the first, but the second I didn't know.
Here is his question:

I have heard a CS Lewis quote about standing on the gap or in the chasm of faith and unbelief and realising that no matter what, one was making a decision - to believe or not to believe. Can you find out what that quote is?

Does anyone know where this is from and what the exact quote is please?

Thanks guys!

[A#minor]

.
Hope you find it.

[Warrior 4 Jesus]

[Guest]

[Warrior 4 Jesus]

[Leslie]

It sounds to me like something out of Mere Christianity, but I can't check because I don't have access to my copy.

[marksbog]

[Warrior 4 Jesus]

[ted]

[ted]

Correction: According to the following site, HCF was changed from LCM (Lowest Common Multiple), which indicates that Lewis probably did mean HCF to mean "Highest Common Factor." Sorry for posted incorrect information too hastily.