Exodus 3 narrates the well-known account of God’s revealing Himself to Moses in the burning bush and commissioning him to tell Pharaoh to release the Israelites from slavery in Egypt. But that was only part of Moses’ mission. The other task to which the Lord called Moses was to address the Israelites. He was to command the Israelites in the name of God to engage in the largest strike in history. In absolute defiance of the power and authority of Pharaoh, they were to leave Egypt and go out to the desert to worship God at His mountain. And, of course, these events ended in the exodus.

Just think of Moses’ task. Moses, an old man who had been tending sheep in the wilderness for years, was to somehow get an appointment with Pharaoh, the most powerful ruler on earth in that day. But in many respects it was even more difficult to go to the people of Israel and say, “Never mind the chariots of Egypt and the armies of Pharaoh. Follow me and I will lead you to the Promised Land.” What slave in his right mind would take Moses at his word? And that is the problem that is addressed particularly in Exodus 4, where Moses says to God, “They will not believe me or listen to my voice, for they will say, ‘The Lord did not appear to you.’ ” And the Lord gave Moses many proofs to show the Israelites that his claims were credible.

In this encounter, Moses raised the question of apologetics, the question of how the believer is to defend the faith as reasonable. He had to convince the Israelites of the truth of the mandate and that it came from God. He was dealing with the in-house problem of apologetics, namely, that he had to persuade the church—the people of God—of the veracity of the Word of God and its claim on their lives.

The task of apologetics, of defending the truth of Christianity, has at least three main aims. I think most Christians are familiar with two of these. First, apologetics is to provide an answer to the critics of the Christian faith, to those who seek to undermine the rational basis for Christianity or who critique it from the standpoint of another philosophy or religion. Paul did that in Acts 17 when he confronted the Epicureans and the Stoics, followers of two popular philosophical schools in his day. Early Christian apologists such as Justin Martyr wrote to the Roman emperor to defend Christians against false accusations of atheism (because Christians did not worship the Roman gods) and cannibalism (because pagans misunderstood the Lord’s Supper).

The second major aim of apologetics is to tear down the intellectual idols of our culture. Here, apologetics operates on the offensive, pointing out the inconsistencies and errors of other faiths and worldviews. The third, and what I believe is the most valuable, aim of apologetics is to encourage the saints, to shore up the church—just as the first concern that Moses had was to be able to demonstrate that God had called him to go to the Israelites and lead them out of Egypt. Moses was an apologist to his own people.

The toughest three years of my life were my seminary years, because I was a zealous Christian studying in a citadel of unbelief. Every day, the precious doctrines of our faith were attacked viciously by my professors. One professor lashed out at a student in my class for coming to seminary with too many preconceived ideas, such as the deity of Christ. Another professor attacked a student when he preached on the cross. “How dare you preach the substitutionary atonement in this day and age!” the professor said. There was a hostility that was palpable in the air, and it was discouraging. All kinds of questions were raised, and even though I understood the philosophical assumptions behind the critics’ attacks, there were still many questions I was not equipped to answer. Intuitively I knew these men were wrong, but I couldn’t answer them.

At that time, there was basically one major seminary in the United States that was faithful to historic Reformed theology—Westminster Theological Seminary in Philadelphia. After classes were over at my seminary for the day, I used to read Westminster professors such as J. Gresham Machen, John Murray, Ed Stonehouse, Ed Young, and others. And they would give me answers to the questions I had. After a while, when I heard a question I wasn’t able to answer, I had confidence that God had raised up great men of learning who knew far more than I did and were able to answer these skeptical questions.

I said to the Ligonier staff many years ago: “The work that we do in apologetics may not be understood in all of the details by all the Christians who hear it. But if we can answer these questions and show the credibility of Christianity, the folks in the church will not be devastated by the voices of skepticism that surround them.” We’ve known students in our churches who’ve gone to college—even professedly “Christian” institutions—and had a crisis of faith. In many cases, they’ve hung on by their fingernails because they were being beaten down every day, ridiculed and scorned for their faith in Christ. What such kids need is the task of apologetics inside the church, to calm their fears. And it is not just college students, it is all of us who live in this fallen world. Because if Satan can’t take away our faith, he might be able to intimidate us to such a degree that we are paralyzed, that we are not quite as bold as we were before. And so, not everybody is called to be a professional apologist, but we are all called to study apologetic issues and to see that there are reasons for the hope that is within us.

This article previously appeared on Ligonier.org, and is used with permission.