Your question is pretty open ended, which perhaps was your point but that doesn't really encourage focused and succinct answers.

As a conservative evangelical Christian the concept of salvation is a central element of my belief system and, really, my entire worldview. The question of what one needs to be saved from is perhaps the best place to start: sin and eternal damnation. Some might elect to use the term "punishment" in place of damnation but I believe the Bible's picture of what awaits the unsaved is better encompassed by the term "damnation." Sin is the fundamental malady of humanity, it is the primary cause of our suffering, and leads irrevocably to death. We are born in sin with a nature that is completely unable to act towards any true moral good because of the generational transmission of a sinful heart from our first parents down to the present day. While we still retain a will that allows us to act the will is tainted by a fundamentally sinful nature. We want to sin and we can not, on our own, change that basic desire. Sin is more than mere disobedience, even if we were to be perfect in our moral behavior we would still be subjects to the taint and penalties of sin because at the core of our being is a desire for autonomy from God and a rebellious heart against Him. Because of sin we all deserve damnation, our offense to God is infinite in scope because of the surpassing holiness and perfection of God and so our damnation is eternal in its duration.

By damnation what is meant is the eternal seperation from the presence and grace of God and tortuous punishment for the disobedience of our lives. Yet, God has willed, under no obligation, to freely offer salvation. This salvation was foretold in the Old Testament by the prophets and foreshadowed in the work done through the lineage of Abraham, Isaac and Jacob and the people of Israel by God. This salvation is redemptive act initiated by God, and because of our utterly helpless estate, and accomplished fully by Him. God used as the means of our salvation the God-Man Jesus Christ. His perfect life fulfilled God's righteous requirements that we could not fulfill and his death served as a means of penal substitution whereby Jesus took on the curse that we deserved and bore it on our behalf. In His resurrection, which must be believed as a literal historical event, Jesus vindicated his claims and showed himself to be victorious over death and to have loosed the chains that bind humanity in sin. But the effects of Jesus' work was not universal in its effects. Jesus died to redeem a particular people, those who would believe and is by the means of the Holy Spirit calling them to himself.

Belief on Christ is the supreme moral good yet as sinful men we are unable to believe apart from God's effective work of grace in us. And for his own glory he is redeeming a great many from eternal damnation through the power of the Holy Spirit. All whom God is calling will believe and will signify their belief through an exercise of faith and repentance that will also culminate in obedience to Christ's commands. Salvation thus occurs when God redeems and regenerates an individual and implants in them a new nature that loves and and seeks God. This is salvation, the gracious work of God to regenerate a sinful and damned person.