1 John 5:13
These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God. These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God.
Eternal life is located in God's Son, so that whoever has the Son has life. That life in the Son is God's gift. Faith in Christ as the one who gives life is what imparts that life. Whoever does not have the Son does not have life.
Those who believe in the name of the Son of God may know with certainty that they have eternal life. This certainty rests on God's testimony and record and on His promises, which provide a secure foundation for faith. Believers carry this testimony, this witness, within themselves.
The required duties and the positive assurance are laid out as plainly as formal guarantee documents, like insurance papers. Those who believe are to trust those promises, keep cultivating and developing their faith, and continue believing in Him. That assurance is not unconditional, since not one sin is removed except through a faith that holds its initial confidence firm to the end, and hope in the complete and entire atonement works only when sin is put away.
The assurance belongs to those who keep His commandments, remain in His love and in His words, bear much fruit, and know the true God by being in His Son Jesus Christ. Whoever remains in Christ does not sin, and whoever practices righteousness is righteous. God in mercy has supplied every facility, resource, and endowment of ability needed to carry out the required duties, and there is only one way to share in the divine nature and escape the corruption in the world caused by disordered desire. Receiving the promised life requires laying aside all self-importance while still valuing character highly because it was purchased at a price, being bought with a price.
This knowledge gives confidence in prayer, so that what is asked according to His will is heard and the thing desired is received. Only the gospel sanctifies the soul and makes possible a life that matches and measures with the measure of God's life.