When Morpheus says this to Neo, that he will have to walk through it, he is
telling him that the choice is entirely up to him. Morpheus can point out the
truth, but accepting it is up to Neo.
God, too, allows us to decide if we will walk through a door or not. He
does not simply open a chasm beneath us so that we fall into His will (although
I think I might be willing for Him to do that so I am not so unsure of myself!)
He leaves us a way out of His will. We can walk through door number 1 or door
number 2. He gives us this opportunity every time. I'm not going to go into a
complete discussion of free-will versus pre-destination here, but I think we can
all agree that, throughout our lives we are faced with the choice of whether or
not we will do something we are sure He doesn't want us to do.
