To salvation faith and repentance are what matters, not charity (though charity will be produce through salvation and its affect on the heart). These two elements, faith and repentance, are the complete grace of God. There is nothing man can do to acquire either one without the grace and selection of God the father.
To sum up: you have free will, but that will would 100% of the time lead you to choose your own damnation over the blood of Jesus. However, God shows special grace to those he wills allowing them to accept the gift which he made on the cross and through his resurrection from the dead. He doesn't violate our will, but he changes and alters it through factors that are so much above our understanding, until it conforms to the outcome that he selected in eternity past.
"No one can come to me unless the Father who sent me draws him, and I will raise him up at the last day." John 6:44.
See that? Unless the father draws us, we do not have it within our sinful natures to come to Christ.
"And we know that in all things God works for the good of those who love him, who have been called according to his purpose. For those God foreknew he also predestined to be conformed to the likeness of his Son, that he might be the firstborn among many brothers. And those he predestined, he also called; those he called, he also justified; those he justified, he also glorified." Romans 8:28-30.
He predestined our calling. There was nothing we could do to ascertain the calling.
Jesus concluded the parable of the wedding banquet with: "For many are invited, but few are chosen." Matthew 22:14. The keyword there is chosen. He chose us that we could choose him.
Or take Romans 11. He cut, he grafted the branches. The branches could not be grafted in of their own volition, but rather were grafted in according to the higher will of God.
Excellent post, Senor Zorro.