It's both the Body and the expanded version of Israel. Not superceding the original but expanding its scope. At least, that's what it's meant to be.

And what do you mean by 'blindly obedient robots listen to their own will'? By definition, they have no will of their own. We do. God created us with free will. We can choose to line up our will with His or not and also to persist in conforming our wills to His or not. By faith I've chosen to do that and by faith and Grace I yet persist. If even Jesus had to work through some serious doubt, who are we to think we shouldn't have to? And I've prayed that last line quite often for nearly thirty years and will probably so continue.

"Knowing one could not have acted otherwise'. That can be true, at least within the context of right relationship with God.