John 6:40 - And this is the will of him that sent me, that every one which seeth the Son, and believeth on him, may have everlasting life: and I will raise him up at the last day.
John 20:31 - But these are written, that ye might believe that Jesus is the Christ, the Son of God; and that believing ye might have life through his name.
Romans 3:28: “A person is justified by faith apart from the works of the law.”
I could go on and on with the bible verses, but I wanted to establish first, that there's only one way by which we can be saved - by believing in our Lord Jesus Christ the Son of God. “God justifies the ungodly (Romans 4:5), both Abraham and David were justified by faith and not by works (Rom. 4:1–8; Gal. 3:6–9), and salvation is “by grace” and “through faith” (Eph. 2:8–9).
What this means is that salvation is a free gift given to those who believe. All you have to do to receive the free gift of salvation is to believe and to confess that Jesus Christ is the Son of God. We cannot earn our salvation by works - you don't have salvation because you are good or because you are generous, you're not going to heaven because you love children, we were saved by grace through faith in our Lord Jesus. So please stop trying to earn your salvation, it's impossible - you have salvation because you believe in Jesus Christ the Son of God.
Simply put, because you cannot "earn" your salvation, you also cannot "unearn" it.
So, now that we know that we know that we can neither earn nor unearn our salvation, does that mean that once we are saved we'll forever remain saved no matter what happens?
No
The simple answer is no
Because though we cannot "unearn" our salvation, there are other ways by which we can lose our salvation. So yes, you can lose your salvation, and go from saved to unsaved.
Think of salvation as a freely given gift - say a MacBook. It's quite expensive but the very generous giver paid fully for it. Heck, they bought it in your name, so all the paperwork carries your name - this means that for all intents and purposes the MacBook is fully yours and since the title is in your name, the gifter cannot collect it back.
They may have paid for it, but they paid for you
Jesus paid it all - for you.
And if you want salvation all you have to do is come to Him and He'll give it to you absolutely free of charge (why are you still refusing His fully paid, no strings attached gift?)
But just like the MacBook, though you didn't pay (and aren't paying) for it so you can't lose it because you defaulted in payments, you can still lose it. Oh yes! And there are many ways.
You may be careless with it and you may throw it away or even reject it!
This is why apostle Paul asks us to work out our salvation with fear and trembling (Philippians 2;12)
Receive salvation, receive the Holy Spirit and allow him to work inside you because if you don't, it'll be like someone with a $10m fully loaded debit card who refuses to use it. One day you'll wake up, look at that card and all you'll see is a piece of plastic. And the devil - ever ready - will come to you and ask you to exchange it for $3.50 bus fare, and you'll give it to him.
Embrace your salvation today.