There is a theological term called eternal security. What this five-dollar phrase means is that once you are saved, you are always saved; you can never lose your salvation.
How can we be so certain of this? You are saved by the grace of God, not by your deeds or actions. You cannot be nice enough, you cannot help enough people, you cannot donate enough money – there is absolutely nothing you can do to earn your way into heaven. And since there is nothing you can do to gain salvation, there is nothing you can do to lose it. Once saved, always saved.
You might ask yourself if you are always saved, then does that mean that you can go out and sin without having to worry about being shut out of heaven? Well, yes, in the literal sense, it does. But if you were sincere in accepting Christ, then you will not want to use this loophole. You will have such gratitude to Jesus for His remarkable gift that you will seek to live your life in a manner that pleases Him.
Now, perhaps some of you may be worried that perhaps you weren’t really saved years ago. Perhaps it was done on a whim or without the proper motivation. If you’re still unsure, you can always ask Him to save you for sure. Read Revelation 3:20 and 1 John 5:11-13. Believe those words of God, and you can know for sure that you have eternal life!