Galatians 3:22 But the scripture hath concluded all under sin, that the promise by faith of Jesus Christ might be given to them that believe.
The Scriptures make it clear that all have sinned. It makes it clear that there is none good enough to get to heaven. Mankind needed to realize that he had sinned so he could accept the promise. Jesus will save all those that believe.
God has shown man that he is a sinner. He has shown man that he is unable to live well enough to get to heaven. He has shown man his helplessness. The Bible shows us that we are sinking and dying in sin with no hope but Christ.
Once we recognize our sin and the fact that we can’t merit salvation in any way at all, then the promise is available for us. We realize we have sinned and can’t fix ourselves. We then believe the promise, and He saves us if we will just believe Him!