That
if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine
heart that God hath raised him from the dead, thou shalt be
saved.
Romans
10:9
The Bible makes it clear what we must do to be saved: confess with your mouth that Jesus is Lord, and believe in your heart that God raised him from the dead. That's it. That's the Good News of Jesus Christ. Salvation is free. You do not earn it. You cannot earn it. Your attempts to earn it are filthy rags.
When you stand at the judgement throne at the end of your life. The accuser, Satan, will be there accusing you of all your sins. Each one of your sins is enough to earn you damnation.
For the wages of sin is death; but the gift of God is eternal life through
Romans 6:23
Have you ever told a lie? You deserve to go to Hell. Ever thought an unkind word? You deserve it. Ever called someone "stupid," "crazy," etc.? You deserve it. The payment for sin is death. Now here's the Good News: if you are saved, Jesus paid the death penalty for you. So as Satan stands before the judgement throne accusing you for all your sins, Jesus stands next to you calmly replying, "I have paid." Jesus paid it all!
And
I give unto them eternal life; and they shall never perish, neither shall any
man pluck them out of my hand.
My Father, which gave them me, is greater
than all; and no man is able to pluck them out of my Father's
hand.
John
10:28-29
When a person is saved, they are saved forever. Don't believe it? Of course not. You are human and that doesn't make sense. But, God says it's so (see John 10:28-29). Jesus paid for all sins - past, present, and future.