John 3:16 For God so greatly loved and dearly prized the world that He [even] gave up His only begotten (unique) Son, so that whoever believes in (trusts in, clings to, relies on) Him shall not perish (come to destruction, be lost) but have eternal (everlasting) life. AMPC

I like this Amplified version of John 3:16 because it amplifies the truth of whoever believes. Believing is as the Amplified Bible states; trust, the one who clings to and relies on Jesus. Believing in Jesus is an action and when we live for Him, think His way, take on His opinion as in relying on Him, then we can say we believe and then we can have eternal life.

It is not a prayer alone but the action of believing, clinging to Him that will bring us to our eternal home with Him.