An insurance policy and justification both have a pretty similar outcome. Both start with me being in the wrong and both end with me in a returned-state; perfected. The debt is paid off, the car/holiness is restored as though it never happened, you know… justified… just-as-if-it-hadn’t happened.
But God’s justification (and the faith that is associated with justification) is not like an insurance policy. Imagine I crashed my car into my Insurer’s CEO’s car… I can do one of two things… I can a) grab my insurance policy and say, “Look, I’ve taken out a policy that says you will make everything ok and pay off my debt!”, or b) I can ask the CEO to forgive me based on his personal mercy.
Being a Christian is latter, not the former… we just happen to know the CEO is a very very gracious guy!
We must be careful not to let our acceptance of God’s promises become the basis of our assurance. God’s promises are the expression of his character – God himself (made known in Christ) is the basis of our assurance; not “our acceptance” or “our faith” in His promises.
Or, to put it another way; don’t think of your faith as eternal-insurance, rather think of God’s grace as eternal-assurance.