The verse plainly states that, since they do not belong to Jesus Christ's Sheep, they do not believe. ON the other hand, being one of Christ's sheep enables one to respond to his call( which correlates with John 6:37). It is not the other way around( that is: if one responds then he becomes one of his sheep). Jesus calls His Sheep and they respond to his call . Hence, that is why In John 6:37, as TOm pointed out, it says that They "Will" come to Christ.

It's not a maybe. See Romans 8:28-30.

This is the problem, Carlos. It is "plainly seen" but not "readily accepted". flee

Amazing grace, how sweet the sound,
Which saved a wretch like me,
I once was lost, but now I'm found,
Was blind, but now I see...