How do we know that eternal life is a promise from God?

The assurance of eternal life stems from God's infallible nature. As mentioned in 1 John 2:25, the promise of eternal life was made by God, who cannot lie. This promise was given before creation, highlighting its eternal significance. Believers are encouraged to have confident expectations for what is unseen and trust in God's promise despite not having physical evidence of eternal life. The very nature of God as faithful and truthful assures us that this promise will come to fruition.