Salvation

A lot of people think that they are going to go to heaven because of how good they are.
However, Bible says we are not saved by our good deeds, it says that we're saved by the gospel - which is the death¹, burial and resurrection of Christ.

We are all sinners:

Romans 3:23:

23 For all have sinned, and come short of the glory of God;

Romans 3:10:

10 As it is written, There is none righteous, no, not one:

And penality for sin is death:
Romans 6:23:

23 For the wages of sin is death; but the gift of God is eternal life through Jesus Christ our Lord.

Jesus says to people who are trusting in their works that He never knew them:

Matthew 7:21-23

21 Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven.
22 Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works?
23 And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.

Jesus saves us and gives us eternal life if we trust Christ alone as our saviour:
John 3:16

16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.

And when you get saved, there is nothing you can do to lose your salvation, hence "eternal" life.

[1] Died for us.

More on eternal security:
[Don Stewart Can a Believer Lose Their Salvation?]
https://www.blueletterbible.org/faq/don_stewart/don_stewart_525.cfm

[Once Saved Always Saved]
https://www.youtube.com/watch?v=hycjHApNNOM

[Pastor Roger Jimenez "Logic Proves Eternal Security"]
https://www.youtube.com/watch?v=IErfjKKY7bI