When we turn from our self-ruled life and turn to Jesus in faith we are saved. Eternal life begins the moment one receives Jesus Christ into his life by faith. Because God gives us eternal life through Jesus Christ, the true believer is secure in that salvation for eternity. Salvation is maintained by the grace and power of God, not by the self-effort of the Christian. It is the grace and keeping power of God that gives us this security.
All true believers endure to the end.
We will either exist eternally separated from God by sin, or eternally with God through forgiveness and salvation. To be eternally separated from God is Hell. To be eternally in union with Him is eternal life. Heaven and Hell are real places of eternal existence. What We Practice Beliefs are not worth much unless they are translated into actions.