To have eternal life we must believe on Jesus Christ. (Jn 3:36) This means knowing that He’s God’s Son (1Jn 3:23), believing He died and rose again (1Th 4:14), and dedicating our lives to obeying and pleasing Him. (Tit 1:16) This is all necessary, but it’s insufficient; believing on Jesus Christ is more than this, much more. We can do all this and still miss Him … finally hearing Him say, I never knew you … and miss everything.
Believing on Christ means entering into God’s rest (He 4:3), and there’s no thoughtful, honest rest unless we’re absolutely sure of eternal salvation, perfectly safe from God’s wrath, as safe as Christ Himself; anything less can’t be rest, so it’s unbelief. (He 4:11) We ought not be satisfied until we find this kind of absolute, eternal rest, striving until we enter the way. (Lk 13:24)
Believing on Christ means repenting (Ac 11:18), turning from self-interest, self-trust and self-dependence (He 4:10), and turning to God. (Ac 14:15)
Believing on Christ means knowing I can’t ever be good enough for God on my own, apart from His grace, but also certain that God’s already imputed perfect righteousness to me (Ro 4:22) as a free gift (Ro 6:23), that He fully accepts me (Ep 1:6) because Christ has become my sin and I have been made His perfect righteousness. (2Co 5:21)
Believing on Christ is sitting at the foot of the cross and looking up at Him dying there, and realizing that He’s dying for me (Ga 2:20), bearing all my sin, past, present and future, and all my iniquity (Is 53:5), paying my sin debt to God, suffering in my place, on my behalf, for me. It’s believing that He’s bought me back from the slave master I’ve sold myself to … and that God Almighty is perfectly satisfied with what Jesus Christ is doing for me. (Is 53:11)
Believing on Christ is knowing with absolute certainty that Jesus Christ has already done absolutely everything that will ever need to be done to secure my eternal acceptance with God, that He has already completely secured this acceptance, that I have been adopted as God’s son (Ga 4:5-6), that perfect righteousness is mine for His sake, and that it always will be. It means knowing I’m as safe from the wrath of God as Jesus Christ Himself. It means trusting fully in the finished work of Jesus Christ as my ultimate and only grounds for acceptance with God.
This is entering into His rest.
Nothing short of this is believing on Christ. (He 4:11) We must know with supernatural knowing, call it faith, that Christ’s work is both necessary and sufficient for our salvation. This knowledge, this peace, this rest, is the work of God (Jn 6:29), a supernatural work in our hearts, minds and souls (Ja 1:18) which produces assurance of salvation (1Th 1:5), delight in God’s law (Ro 7:22), and a life pattern of good works. (Ep 2:10) It produces eternal rest, righteousness and peace. (Is 32:17)
We will never get here by working for it, by trying to be good, or by performing any kind of ritual. Believing on Jesus Christ requires a miracle (Mt 19:25-26), and God is offering this miracle to anyone who’s unwilling to live without it. (He 11:6)