Wayne Grudem, in Systematic Theology, has some words on “proofs” for the existence of God. These same ideas are equally applicable to the whole field of apologetics, in my opinion…
The value of these proofs, then, lies chiefly in overcoming some of the intellectual objections of unbelievers. They cannot bring unbelievers to saving faith, for that comes about through belief in the testimony of Scripture. But they can help overcome objections from unbelievers, and, for believers, they can provide further intellectual evidence for something they have already been persuaded of from their own inner sense of God and from the testimony of Scripture.
- Systematic Theology, Wayne Grudem.
In other words, apologetics cannot change unbelievers’ minds, it can only defend the position believers already know to be true. This fits with the Scriptural basis for the study of apologetics as a defense, not an evangelistic argument:
1 Peter 3:1515 but in your hearts honor Christ the Lord as holy, always being prepared to make a defense to anyone who asks you for a reason for the hope that is in you; yet do it with gentleness and respect, (ESV)
It also fits what Scripture tells us about the unbeliever’s ability to understand spiritual truth without the presence of the Holy Spirit:
1 Corinthians 2:1414 The natural person does not accept the things of the Spirit of God, for they are folly to him, and he is not able to understand them because they are spiritually discerned. (ESV)
How many times do we find ourselves wondering why unbelievers don’t believe? Wonder no more – they do not and cannot receive the things of the Spirit of God.
John 12:37-4137 Though he had done so many signs before them, they still did not believe in him, 38 so that the word spoken by the prophet Isaiah might be fulfilled:
“Lord, who has believed what he heard from us,
and to whom has the arm of the Lord been revealed?”39 Therefore they could not believe. For again Isaiah said,
40 “He has blinded their eyes
and hardened their heart,
lest they see with their eyes,
and understand with their heart, and turn,
and I would heal them.”41 Isaiah said these things because he saw his glory and spoke of him. (ESV)