When it comes to thinking about testimonies and professions of faith, one helpful clarifying question we often use is this: if you were to die today and find yourself stood before the Lord, do you think you will be going to Heaven or not? If so, on what basis? If not, why not?
The reason the question can be helpful is it clarifies the grounds upon which a person is basing their faith. We are hoping to hear something along the lines of ‘because Jesus has paid for my sin and so there is no reason I shouldn’t be allowed in’ or simply ‘because Jesus promises those who believe in him will enter, and I trust in Jesus’. Fundamentally, we want to hear some sense that faith is grounded in Jesus alone and as such there is some confidence in future glory.
Of course, that question isn’t perfect. Sometimes when you ask whether someone is sure of going to Heaven, they say ‘no’. What then? Does this mean they aren’t a believer? Well, not necessarily. The question when somebody says ‘no, I’m not certain I’ll go to Heaven’ has to be ‘why not?’
There are two different kinds of people who might answer ‘no’. On the one hand, you have genuine believers who lack assurance. They believe by faith in Jesus, they believe their sin has been forgiven, but they nevertheless lack assurance about their eternal state. They might simply not fully understand the mechanics of what happened on the cross or they might lack doctrinal understanding about union with Christ or any other key doctrinal idea. It’s not that they fail to believe the gospel or trust in Christ, they just haven’t grasped the fullness of its mechanics and thus lack assurance.
On the other hand, there are those who don’t understand the gospel or who aren’t trusting in Christ alone and thus lack assurance because they don’t really believe the gospel. These are the folk who say ‘no, I’m not sure’ because they are still trusting in their works or in some other fallible means other than Jesus. Their lack of certainty isn’t just a misunderstanding of the mechanics of the atonement, it is a fundamental trust in the wrong thing.
But both these people initially present the same way. You ask them if they are certain of Heaven and they answer ‘no’. But when you probe into why, it soon becomes clear. Sometimes you can tell from other answers to questions already asked.
If they’ve already told you they are trusting in Jesus, that they aren’t trusting in their works and they are confident their sin has been forgiven, you can surmise you are dealing with someone who lacks assurance because they haven’t joined all the dots. You can walk them back through the answers they’ve already given, ask them what they think keeps them out of Heaven, remind them that they’ve already said they’re confident their sin has been forgiven and help them join the dot themselves. Often the light goes on and it is evident it was simply not understanding the mechanics so much as not believing in Christ.
By contrast, if they haven’t given you any great sense that sin is the fundamental issue or that faith in Christ alone is the solution to it, you can will want to probe into this. If they aren’t sure they are going to Heaven, the question is: what do you think keeps you out of Heaven? Why has/hasn’t that issue been fully dealt with (as you understand it)? This very often teases out a belief in Christ plus works and so one is not sure of their salvation because they have not necessarily done enough to merit it. This evidences a more fundmental lack of understanding that has stopped a person believing in Christ alone and this (per Galatians) not having the gospel at all.
The question about Heaven is clarifying, but it isn’t final. It can sometimes clarify if a person is trusting in Christ alone and is confident that their salvation is secure simply because of him and all he accomplished on the cross. At the same time, it may highlight a lack of assurance. That is where we need to poke around a bit more and discover whether this is a result of failure to understand the mechanics of the atonement or particular non-salvific (albeit important) doctrines or whether this lack of assurance is a specific product of not really understanding the gospel at all and failing to put ones trust in Christ.