Effective Scope of Atonement

He is the propitiation for our sins, and not for ours only but also for the sins of the whole world. (1 John 2:2 ESV)

Jesus died for the sins of the whole world. Then why are not all men saved? Why does the scope of atonement appear to be limited?

For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: Not of works, lest any man should boast. (Ephesians 2:8-9 KJV)

We are saved by grace through faith.

For "everyone who calls on the name of the Lord will be saved." How then will they call on him in whom they have not believed? And how are they to believe in him of whom they have never heard? And how are they to hear without someone preaching? And how are they to preach unless they are sent? As it is written, "How beautiful are the feet of those who preach the good news!" But they have not all obeyed the gospel. For Isaiah says, "Lord, who has believed what he has heard from us?" (Romans 10:13-16 ESV)

The grace of God is upon those who have heard and believed.

For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek. (Romans 1:16 ESV)