Jesus Christ took upon Himself the sins of the whole world and brought a means of reconciliation to God. There is one exception, and that is rejecting the drawing and leading of the Holy Spirit.
Jesus Christ died to save all mankind.
The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that ALL should come to repentance. - 2 Peter 2:9
For if, when we were enemies, we were reconciled to God by the death of his Son, much more, being reconciled, we shall be SAVED BY HIS LIFE. - Romans 5:10
Jesus Christ paid for all our sins upon the cross.
The whole world is reconciled to Jesus Christ by what He did on the cross, but the whole world is not saved because their sins are forgiven. We must receive the Spirit of God (be born again) in order to be saved.
The Islams, Bahai's, Buddhists, Atheists, etc... who blaspheme against the Holy Spirit will not be pardoned from their sin.
Wherefore I say unto you, All manner of sin and blasphemy shall be forgiven unto men: but the blasphemy against the Holy Ghost shall not be forgiven unto men. - Matthew 12:31
The whole world is reconciled to God by the death of His Son. Reconciliation does not mean everyone is saved; it means that the enmity between God and mankind as a result of Adam's transgression has been reversed. True salvation is having faith in the resurrecting power of Jesus Christ. Receiving His resurrected life is having the indwelling of the Holy Spirit in you.
Most modern "churches" will tell you that your sins must be forgiven in order to be saved, but true salvation is the result of having Jesus Christ in you (being filled with the Holy Spirit).
Confessing our sin is the admission that we need a Savior, but that is not the fulfillment of salvation. We must have faith in the death and resurrection of Jesus Christ to be saved.
The true Gospel of Jesus Christ must include His resurrecting power.