You mean like you calling Particular Baptists "Calvinists?"
So, which part of man, body, soul, or spirit do you think avoided the consequences of the fall and remains in perfect holiness and merits God's grace?
Sufficient for all, efficient only for believers. And I am not sure what you mean by "available." The atonement is not "available" to us as it is not offered to us. The atonement was offered to God by the Lord Jesus Christ. The atonement is offered to the injured party. Our sin, as David says, is "Against you (God), and you only, I have sinned" (Psalm 51:4). It is the results of the Atonement, the forgiveness of our sins, that is applied to us by the Lord.
They are the same thing.
Matthew 20:16 So the last shall be first, and the first last: for many be called, but few are
chosen (εκλεκτος).
Ephesians 1:4 even as he has
chosen (εκλεκτος) us in him before the foundation of the world, that we would be holy and without defect before him in love;
Matthew 24:24 For there shall arise false Christs, and false prophets, and shall shew great signs and wonders; insomuch that, if it were possible, they shall deceive the very
elect (εκλεκτος).
Colossians 3:12 Put on therefore, as the
elect (εκλεκτος) of God, holy and beloved, bowels of mercies, kindness, humbleness of mind, meekness, longsuffering.
Which, of course, has nothing at all to do with the bible doctrine of "irresistible grace" (which I admit is a poor way of stating it, probably invented by a Baptist Preacher so the letter fit the TULIP acronym). The better word would be "efficacious" grace. When the regenerating grace of God is applied to the sinner it always accomplishes what God intended it to accomplish. The Grace of God never fails, but is always efficacious. It always accomplished what God intended it to accomplish.
And, of course, no Calvinist believes a person must persevere in order to be saved. They believe that the saved are "preserved" in Christ until the end.
Jude 1 "Jude, the servant of Jesus Christ, and brother of James, to them that are sanctified by God the Father, and
preserved in Jesus Christ, and called."
We are not saved because we persevere. We persevere because we are preserved in Christ.
Yes, it is a sad fact that many preach against the Grace of God, the Sovereignty of God, the Election of God, the very Gospel itself out of ignorance as displayed above.