Simply put, salvation is purely a New Testament Christian construct. Salvation is the being free from everlasting death.  This death is a total separation from the only true and living God, the God of Abraham, Isaac, and Jacob, who manifested Himself through the Virgin Birth in the Lord Jesus Christ.

Adam and Eve, our first parents sinned against God by committing what could be termed high treason.  This offense was so great that only death could satisfy this lack of trust in the perfect, all knowing, all powerful, all present, never changing, God who is LOVE and TRUTH, and Who having no beginning and no end, is eternal.  However, God is also a Consuming Fire, according to Hebrews 12:29. This speaks of dealing with evil, in that evil in any form is a denial of TRUTH.  It’s all about THE TRUTH vs. THE lie.

God, in His love, provided the way out for all mankind, if mankind were to accept this way out, by trusting Him.  It always comes down to TRUSTING in the only true and living God, the God of the Bible.  Instead of judgment, which is the only way for true justice to be served against those who purposefully violate the truth, mankind would be pronounced totally free from their sin guilt. Those now legally free from sin are worthy to be in the presence of Almighty God forever and share great rewards in His Kingdom - both - spiritually and earthly.

The state of being for those who do not accept this free pardon for sin is a different story. God, being perfectly just, will give all those who refuse to acknowledge their sin and come to Him exactly what they not only deserve, because of true justice but what they unwittingly ask for - playing god themselves. The state of their existence in eternity is total and complete separation from Him Who is not only LOVE and TRUTH, but also LIGHT.  A place called the Lake of Fire (Rev 19:20; 20:10; 21:8) is reserved for the devil and his angels and for any people who side with them in open rebellion towards the LORD GOD. (Matt 25:41) Jesus spoke much about the torment and suffering of those who despise God by not simply trusting Him.  He spoke more of the negative than the positive concerning this issue of salvation.

 SALVATION IS WHAT KEEPS US FROM THIS END FATE!  All it takes is trusting (having faith) in God.  Romans 10:9 &10 states, “That if you confess with your mouth, the Lord Jesus, (believe that He is Lord/God the Son) and believe in your heart that God (the Father) has raised Him from the dead, (by the power of God the Holy Spirit) you will be saved.  For it is with your heart that you believe and are justified, (just as if you’d never sinned) and it is with your mouth that you confess and are saved (Speaking words of confession).”  (Parenthesis mine)

There is no such thing as annihilation of the soul.  What God creates stands. “That which was created cannot be uncreated!” (Irenaeus: Against Heretics; 2nd Century) All -  saints (those who are saved) and sinners alike -  will exist in one of two places.  Either we will be with God, in unimaginable bliss and joy, or we will be without God in unimaginable suffering and torment in the Lake of Fire.  Both possibilities are eternal thus, they are without end.