You sound like a brilliant Jesuit of the Counter-Reformation -- that's a compliment! I don't subscribe to
Calvinist doctrine (remember TULIP?) but I'll try to play
Devil's Advocate (Calvin would like that term!) The
paradox you cited is what many say is the Achilles' heel
of his theology. It goes (again, oversimplification!)
something like this: If EVERYTHING is predestined --
unconditional election - then what does it all matter?
But Calvin did say the we should live AS IF we had free
will and try to comport with the Gospel imperatives
for the simple reason that NO HUMAN can fathom the divine
mystery concerning election -- and FURTHERMORE!! -- if
you act as though YOU know you are among the elect or
the damned -- you are being filled with the sin of pride
and assuring your own fall! A story is told about Cotton
Mather giving his notorious sermon, "Sinners in the Hands of an
Angry God" to his Calvinist comngregation in New England
-- but that can wait.
Jonathon Edwards is famous for that particular sermon