The preaching of the cross is foolishness to those who have not been liberated by the new birth. I think it's easier to deal with questions about the authenicity and authority of the Bible first, before you "argue from Scripture" to support a doctrine (other than the inspiration and infallibility of Scripture).

It seems to me that a lot of the argument in the original post is simply unfruitful because both sides share a belief in the myth of so-called "free will." Ain't no such thing for unbelievers. They are slaves, bound to sin, held captive in its power and incapable of anything else. Only Christians have free will because we have been freed from the law of sin and death. The unregenerate rebel has "choice" only within his or her ability. The attempt at "apologetics" above proceeds from at least that one false assumption.

The origin of faith in the original post is another false assumption. Saving faith is not something that grows out of our own experience. According to Ephesians 2 it is the gift of God, not of works. The inward call and the new birth are acts of God upon individuals, not little enricements to get people to choose Christ.

The false assumptions and absurdities in this "argument," if accepted, might result in someone being persuaded to pray "the sinner's prayer" and fill out a card, but true conversion results not from the persuasive words of clever apologists, but from the demonstration of the God's power in and upon His chosen people.