"Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved;)" (Ephesians 2:5). This says that even though we were laden with sin and we were set for eternal death and damnation, God brought us back to life and gave us the same gift that He gave his one and only son, Jesus Christ. Through these verses in Ephesians and other books, we can see that there is only one way to have eternal life and therefore I and my friend have to accept that we are not perfect in God's eyes, but yet He loves us so much anyway and He is able to use his abundant mercy and grace to gives us sinners eternal life. The only thing we have to do is believe and have faith in Jesus Christ. There is no other way: Jesus Christ is the way, the truth, and the light.

Ephesians 2:7 explains "That...

God will never save us and then turn his back and take it away. This is His promise to us and so there isn't any need to worry that there will be a time when God won't was away our sins.
The benefits of eternal life is that we will all live forever in God's Kingdom. Belief in Jesus gives us a space in God's Kingdom. This is where our soul goes to live when our physical body dies. but, we can have eternal life while we are still on this earth because by accepting Jesus, God lives within us. So we can have God in our physicality, in our soul, upon this earth, and we will go to live within Him when we have cast off our physical shell.