The classic verse promoting apologetics (the defense of the Christian faith) is as follows.."But sanctify the Lord God in your hearts: and be ready always to give an answer to every man that asketh you a reason of the hope that is in you with meekness and fear:" 1 Peter 3:15
The only way to do this effectively is to study the reasons why we believe what we believe. This will prepare us as Paul states.."Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ” 2 Corinthians 10:5
Paul practiced what he preached; in fact, defending the faith was his regular activity (Philippians 1:7). He refers to apologetics as an aspect of his mission in the same passage (v.16). He also made apologetics a requirement for church leadership in Titus 1:9. Jude, an apostle of Jesus, wrote.."Beloved, when I gave all diligence to write unto you of the common salvation, it was needful for me to write unto you, and exhort you that ye should earnestly contend for the faith which was once delivered unto the saints.” Jude 3
Jesus was His own apologist, as He often stated that we should believe in Him because of the evidence He provided (John 2:23; 10:25; 10:38; 14:29). In fact, the whole Bible is full of divine miracles that confirm what God wants us to believe (Exodus 4:1-8; 1 Kings 18:36-39; Acts 2:22-43; Hebrews 2:3-4; 2 Corinthians 12:12). People rightly refuse to believe something without evidence. Since God created humans as rational beings, we should not be surprised when He expects us to live rationally. This does not mean there is no room for faith. But God wants us to take a step of faith in the light of evidence, rather than to leap in the dark.
Those who oppose these clear biblical teachings and examples may say, “The Word of God does not need to be defended!” But which of the world’s writings are the Word of God? As soon as someone answers that, he is doing apologetics. Some claim that human reason cannot tell us anything about God—but that statement itself is a "reasonable" statement about God. If it’s not, then there is no reason to believe it. A favorite saying is, “If someone can talk you into Christianity, then someone else can talk you out.” Paul himself gave a criterion (the resurrection) by which Christianity should be accepted or rejected in 1 Corinthians 15. It is only misplaced piety that answers in the negative.
None of this is to say that apologetics alone, apart from the influence of the Holy Spirit, can bring someone to saving faith. This creates a false dilemma in the minds of many. But it does not have to be “Spirit versus Logic.” Why not both? The Holy Spirit must move someone to a position of belief, but how He accomplishes this is up to Him. With some people God uses trials; in others it is an emotional experience; in others it is through reason. God can use whatever means He wants. We, however, are commanded to use apologetics in as many or more places as we are told to preach the gospel.