It's the most important question a person can ask — and the good news is that the Bible gives a clear answer. It's simple enough that a child can understand it and certain enough that you can know today whether you have eternal life.
So here it is.
Scripture states the condition for eternal life over and over, and it always says the same thing: believe in Jesus Christ.
"For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life." — John 3:16
Notice what Jesus requires. Not "whoever believes and obeys." Not "whoever believes and cleans up his life." Whoever believes.
A jailer in Philippi once asked the same question you're asking, and he got a one-sentence answer:
"Sirs, what must I do to be saved?" So they said, "Believe on the Lord Jesus Christ, and you will be saved, you and your household." — Acts 16:30–31
Paul had every opportunity to add a second requirement. He didn't. The man asked what he must do, and Paul told him there was nothing to do but believe.
Paul explains why in his letter to the Ephesians:
"For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, not of works, lest anyone should boast." — Ephesians 2:8–9
Salvation is a gift. Gifts aren't earned, or we'd call them wages. And if you could contribute even a little to your salvation, you'd have something to brag about — which Paul says is exactly what God has ruled out.
Jesus said it most plainly of all:
"Most assuredly, I say to you, he who believes in Me has everlasting life." — John 6:47
Not will have. Has. Present tense. The moment you believe, eternal life is yours.
To believe in Jesus is to be persuaded that He is who He says He is — the Christ, the Son of God who died for your sins and rose again — and that He alone can give you eternal life.
That's it. There's no prayer you must recite, no aisle you must walk, no ritual to complete. Those things can be meaningful expressions of faith, but none of them is the condition. The condition is faith.
If you believe Jesus' promise, you have everlasting life right now.
