Again, the two truths are not identical, but they are related to each other. They reject God's sovereignty in salvation, thereby destroying the theological basis for eternal security and assurance. It asserts that if a Christian thinks he is secure forever, he is apt to become spiritually negligent. The final perseverance of the saints is one of the grand and distinctive blessings proclaimed by the Gospel, being an integral part of salvation itself, and therefore any outcry against this doctrine is an attack upon the very foundations of the believer's comfort and assurance. Assurance is an inextricable part of saving faith.
Assurance concerns the realization that a person has eternal life.
But security is a true fact whether or not an individual has assurance of that or not. Eternal security is a doctrine of Scripture, a divine revelation of an abiding fact which exists, whether it is believed or not. Assurance is only the personal confidence in a present salvation. Now, God wants you to enjoy your salvation. He never lets go.