By nature, all human beings are born into sin and shaped by iniquity. Each human being comes into the world possessing a sinful nature that constitutes him a sinner by birth. This sinful nature, in time, is evidenced by sinful thoughts, words, deeds and an attitude of enmity to God. The Bible makes this abundantly clear.
As Christ willingly hung upon the cross, He assumed the full liability of our guilt and sin, bore our sins in His own body, and died as a substitutionary sacrifice on behalf of all sinners. All God's judgment against sin fell on Him, and all God's righteous claims against the sinner were fully satisfied by Christ's death on our behalf. God indicated His complete acceptance of this sacrifice of Christ by raising Him from the dead and seating Him at His own right hand.
Since Christ has accomplished (by the sacrifice of Himself) all the work needed for the sinner's salvation, what must the sinner do in order to experience this salvation?