Christ's death was for all men. Right now, every sin anyone ever did has already been paid for by Christ's blood. God's holy character demands payment for every infraction against His righteousness.
From God's POV, all such debts have been fully satisfied because of Christ's death on our behalf. On this truth, the invitation of the Gospel can be extended to all men.
Otherwise, preachers of the Gospel lie when calling all to Christ as they are commanded and commissioned to do. They cannot, with integrity, call to salvation someone whose sin debt has not already been satisfied by Christ.
So Christ died for sin because He was the only One who could. Sinless blood is the only atonement God's holiness could and would accept in payment. Sinner's can never pay for their own sin...all are bankrupt without Christ.
Limited Atonement, an evil doctrine of Calvinism, teaches Christ only died for those God had selected before time began. This cannot be, as it would leave a huge debt on the part of sinners still owed to God through out eternity. A sinner, as we shall presently see, can only pay for one sin with his eternal soul.
God's justice can only be fully satisfied by Christ's blood and in God's sight, this was already accomplished by Christ before the world began. Not one sin, however seemingly insignificant, will ever go unpaid, or God is complicit in that anomaly by allowing it to breach the Laws of His righteousness.
All truth of God must be clarified, and this doctrine is no exception. I am not teaching universalism, that perversion of God's Word of grace.
Not all are saved because Christ died for them. Each person must accept God's free and gracious invitation to "believe on the Lord Jesus Christ" and be saved. Each person must be "born-again" by coming to Christ, the giver of eternal life. Christ knows His sheep, and logic demands they know Him as well.
A refusal to come to Christ, whom the Spirit is exalting in His witness to a lost world as the only Redeemer, is the sin against the Holy Spirit.
This is the one sin not covered by Christ's atonement and those who commit it shall pay for it and only it, by their spiritual death...separation from God forever. God's scales of justice will be eternally balanced, or God is not God.
Let us believe the happy truth Jesus gave as His motivation for living and dying, "I have come to seek and to save sinners."
Those who seek Him who is seeking them, will soon find the Captain of their salvation, the hero of Calvary, the ever living One, the Lord Jesus Christ.
Now then, we are ambassadors for Christ, as though God were pleading through us: we implore you on Christ's behalf, be reconciled to God. 21 For He made Him who knew no sin to be sin for us, that we might become the righteousness of God in Him. 2 Corinthians 5:20
Author's notes:
Christ did not come to condemn us. We were already condemned by our sin to be separated from the Holy One, God. He came to give us freedom to walk with God without a bad conscience and thus progressively become more like Him. This walk culminates in Heaven and involves a final consummation in righteousness so we are truly good and pure, fitted by His grace to enjoy God's Presence and eternal Heaven.