Church Fathers/Early Patristic Period
In the first century after the apostolic era, we see right away the rich work of Christian Apologists emerging. Justin Martyr wrote several works of apologetics in the 2nd century AD interacting with Greek philosophical concepts and defending the faith through rational discourse. It was not simply an intellectual game for Justin as he was executed AD 165. His crime was defending Christian teachings in a debate with a cynic philosopher named Crescens. Furthermore, in the third century, an early follower of Jesus named Origen wrote a work entitled Contra Celsum giving an answer to a Platonist philosopher named Celsus. Apparently this guy was accusing Christians of being dumbs-dumbs and Origen sought to intellectually refute his claims.
Augustine of Hippo
When we arrive in the fifth century we encounter the massive literary efforts of St. Augustine of Hippo. A massively influential (and controversial) theologian to this day, he also wrote a significant apologetic to the detractors against Christianity in his day. Augustine was a bishop in the church after the times of Constantine when Church and Roman Empire had effectively become one. The ideology of that time merged the idea of Rome as the eternal city with the idea that it was the culmination and arrival of the Kingdom of God. The crucified and risen Jesus had brought the world-dominating Roman Empire to heal and therefore it was to be the crown of the work of God on the earth. Then something happened. Alaric, King of the Visigoths sacked Rome and the already crumbling Empire was shown to be something less that the Kingdom of God. In this time, many pagan thinkers accused this fall of Rome on it switching its gods to the worship of Jesus. The fall of Rome, so they said, was the fault of the people abandoning the traditional gods in favor of Jesus and the Christian religion. It was in this setting that Augustine wrote his now classic City of God, which laid forth a Christian view of history and separated the city of man and the rule and reign of Jesus. Jesus’s church always traveled among the city of man but the two were not to be seen as one; they were, in fact, at odds with one another. Political rule and the rule of the King of heaven were not to be collapsed into one. They are separate. The interesting thing about Augustine is his methodology of entering debate with the pagans. He refuted their claims and then told the greater narrative of the Kingdom that has no end which should not be identified with Rome…or America for that matter.
Later in the thirteenth century, Thomas Aquinas, the looming medieval luminary, engaged in a similar apologetic project with the Islamic thinking of his day. Leading up to this time the ancient works of Aristotle had been rediscovered by Arabic thinkers and were leading to various advances in natural philosophy, ethical reasoning, mathematics and logic. At the time, Christian Europe was introduced to Aristotelian thinking through the translated works of the Muslim philosopher Averroes. In the mid thirteenth century, Thomas wrote his work Summa Contra Gentiles as an answer to the Islamic thinking that was pouring into Europe. For several hundred years Islamic forces had sought to conquer the European continent by force of arms and had succeeded in fully annexing the Iberian Peninsula. Many know that Charles the hammer Martel fought back the Islamic invasions militarily but fewer today know that the intellectual bastions of Europe were manned by Christian theologians and apologists such as Thomas Aquinas. He interacted with Aristotle, created a unique synthesis between faith and philosophy and, as some would argue, set the table for the scientific revolution which took place in Europe in the centuries that followed.
Early Modern and Modern Apologists
Even further along in history we find the 17th century French philosopher and mathematician Blaise Pascal wagering with the skeptics of his day. Closer to our own times we find British thinkers GK Chesterton, Dorothy Sayers, Malcom Muggeridge and CS Lewis calling out in the wilderness of the crumbling Christian civilization of Great Britain. We observe the American thinker Frances Schaeffer pushing the West to examine its effort to deconstruct itself. In our own day men like Francis Collins, Michael Behe, William Dembski, Alister McGrath and John Lennox are interacting with the modern sciences when that enterprise overstates a naturalistic case. Apologist Ravi Zacharias engages the existential issues of the day and men such as William Lane Craig are doing philosophy in the public sphere of intellectual debates on topics such as the existence of God, the objectivity of moral values and the historical resurrection of Jesus from the dead.
In summary, we observe both in the New Testament Scriptures and in the pages of church history that God’s people are exhorted to contend for the faith once for all entrusted to the saints (Jude 3). Pascal describes well the apologetic enterprise of the people of God in his classic work Pensées:
Men despise religion. They hate it and are afraid it may be true. The cure for this is first to show that religion is not contrary to reason, but worthy of reverence and respect. Next make it attractive, make good men wish it were true, and then show that it is. Worthy of reverence because it really understands human nature. Attractive because it promises true good.
It is the work of God to convert and convict people of sin and allow them to see the light of the gospel in the face of Jesus Christ. We are to preach the gospel as it is the power of God for the salvation of all who believe (Romans 1:16). We are also to give a reason for the hope we have, doing so with gentleness in our flow and respect for people (1 Peter 3:15). The ways in which we may go about the apologetic task is the focus of the next section.
 The apostolic age or era simply refers to the first generation of Christians after the death and ascension of Jesus. This age comprises the bulk of first century Christianity and includes the work of the apostles and that of those known as the apostolic fathers (Clement of Rome, Ignatius of Antioch, Polycarp of Smyrna).
 See Curtis Chang, Engaging Unbelief : A Captivating Strategy from Augustine & Aquinas (Downers Grove, Ill.: InterVarsity Press, 2000). Chang lays forth a strategy for apologetics derived from these two historical Christian leaders who served at different historical epochs. What he finds in common with both Augustine and Thomas is that they entered debate with Christianity’s critics with their terms, exposed the flaws in their arguments and then captures the truth they were getting at retold within the Christian story.
 The most influential thinker along these lines is Pierre Duhem and his massive work Le système du monde: histoire des doctrines cosmologiques de Platon à Copernic (The System of World: A History of Cosmological Doctrines from Plato to Copernicus. For an introduction to Duhem, see Roger Ariew, “Pierre Duhem,” Stanford Encyclopedia of Philosophy (2011). http://plato.stanford.edu/archives/spr2011/entries/duhem/ (accessed 9/14/2011). See also
 See Markos. Louis Markos new work focuses several chapters on the thought of Chesterton, Sayers and Lewis. For those wishing to be introduced to these British apologists Markos book is to be commended.
 Francis A. Schaeffer, Francis A. Schaeffer Trilogy: The Three Essential Books in One Volume (Wheaton: Crossway Books, 1990).
 See Francis S. Collins, The Language of God : A Scientist Presents Evidence for Belief (New York: Free Press, 2006). Michael J. Behe, Darwin’s Black Box : The Biochemical Challenge to Evolution (New York: The Free Press, 1996). William A. Dembski, The Design Revolution : Answering the Toughest Questions About Intelligent Design (Downers Grove, Ill.: InterVarsity Press, 2004). John C. Lennox, God’s Undertaker : Has Science Buried God?, 1st ed. (Oxford: Lion, 2007); Alister McGrath, A Fine-Tuned Universe: The Quest for God in Science and Theology (Louisville: Westminter John Knox, 2009).
 His early work reflected lectures given on various college campuses in the early 1990s – see Ravi K. Zacharias, Can Man Live without God (Nashville: W Pub. Group, 1994).
 Craig’s summary work is his textbook William Lane Craig, Reasonable Faith - Christian Truth and Apologetics, 3rd ed. (Wheaton: Crossway, 2008).
 Quoted in Douglas Groothuis, Christian Apologetics - a Comprehensive Case for Biblical Faith (Downers Grover: IVP Academic, 2011), 25.