Where is our assurance based?

So where is our assurance based? It is based in Christ. “He who has the Son has the life” (1 Jn:5:12He that hath the Son hath life; and he that hath not the Son of God hath not life.
See All...). If we really believe and trust that Jesus is the Christ, died for our sins, and rose from the grave, we have life assurance now and forever because we have the guarantee of the Holy Spirit testifying to our spirits (Eph:2:13-14 [13] But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ. [14] For he is our peace, who hath made both one, and hath broken down the middle wall of partition between us;
See All...; Rom:8:14-17 [14] For as many as are led by the Spirit of God, they are the sons of God. [15] For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father. [16] The Spirit itself beareth witness with our spirit, that we are the children of God: [17] And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together.
See All...). Further, if we are truly born-again there will be a change in our lives. If we focus on what the New Testament teaches regarding being “in Christ”, there will be more evidence of faith in our lives than if we focus on our own obedience. 

“And the testimony is this, that God has given us eternal life, and this life is in His Son…These things I have written to you who believe in the name of the Son of God, so that you may know that you have eternal life” (1 Jn:5:11And this is the record, that God hath given to us eternal life, and this life is in his Son.
See All..., 13).

—Dale Ratzlaff (1936–2024, Pastor and Founder, Life Assurance Ministries, former Seventh day Adventist).