Christian apologetics - the pursuit of demonstrating the evidence and providing reasons for the truth of the Christian worldview - is commanded in Scripture. Those familiar with Christian apologetics will likely know at least some of how this is best done to be both Scripturally sound and persuasive.
If you think that apologetics is unnecessary or competes with the Holy Spirit in drawing believers, you have the wrong picture. Scripture commands us not only to believe but also to be able to defend the truth of Christianity. Consider the fact that Christ said that we must love God with our minds as well as with our heart, soul and strength (Luke 10:27). Consider that Peter commands us not only to revere Christ as Lord but also to "always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have" (1 Peter 3:15). Unfortunately, most Christians do not take this command seriously. I admit that beginning to defend the Christian worldview can be a daunting task. The barrage against Christian beliefs takes no rest on the internet and in the public square, and intimidation is rampant. However, given our delegated responsibility, we have to start somewhere.
As in the insertion of a bud or shoot of one plant into another found in horticulture, the Christian life can and should be augmented by the grafting of the shoot of the life of the mind with the life of the heart. I've come up with a mnemonic device, "GRAFTERS," to help make it easy to memorize. And if you're already familiar with Christian apologetics, this may offer some helpful tips to help improve in your endeavors.
Find opportunities to discuss ideas with people of different belief systems. Learn. Improve your knowledge and tactics consistently. One of the best tools at your disposal is Tactics by Greg Koukl. Clarify. When given objections that are not immediately clear, get clarification before you answer or research the topic. Too often, one may find an answer to a question one merely thinks is being presented when the person meant something entirely different. This is a waste of time and makes you look bad.
When faced with objections you've never heard before, try to get clarity and get more acquainted with the objection before making any bold responses. If you don't know, ask. There are many groups available to provide you with answers or at the very least, point you to resources where you may find those answers. One such group is the Christian Apologetics Alliance. If you're not plugged into a group, it would be a good idea to do so now.
Read as much as you can. Start with introductory apologetics books and read increasingly more advanced materials. To retain the information you read, it's best to take notes. It's preferable to handwrite your notes. Handwriting has been proven to help improve retaining information much better than any other form of notetaking.
It's good to have a broad understanding of various arguments but try to keep your reading materials leaning heavily towards a specific topic of your choosing (more on this later).
For online reading, one of the best things to do is to save the information you read. Use technology to aggregate information. One of the best tools for doing this is Evernote. It allows you to pull entire web pages and allows you to save them with labels into notebooks that are also available to you offline. And since you're making actual copies of the information and not merely bookmarking, and since the information is automatically backed up in the cloud, you will never lose that information even if a web page you saved is taken offline in the future.
As you grow in knowledge, you may be tempted to pursue means of demonstrating that knowledge which may not be gracious and compelling.
Practice self-restraint; being equipped with knowledge is not a carte blanche to try to intimidate people. Try to put yourself in the shoes of the people with whom you interact. How would you want to be treated? Try to imagine yourself being unaware of facts or making the mistakes you see others make. How would you like to be persuaded and helped out of error and falsehood?
Try to bear in mind that despite the very many things you learn, there are going to be volumes that you still don't know and even more that you will never get to learn. Keep that in mind when presenting arguments and approach matters with humility.
It can be a challenging thing to do but be as gentle as possible with people. It's not only the right way to approach matters but the biblical way in which to do so - be kind and gracious. As Peter stated,
"But in your hearts revere Christ as Lord. Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect..." (1 Peter 3:15)
Without a doubt, there will be instances when no matter what kind of compelling reasons you offer, the person to whom you present them will not be convinced. Don't expect people to immediately discard the beliefs they've held for long periods of time, in some instances for all of their lives. Expect resistance. Sometimes this means leaving the person with some food for thought and moving on. Look back on the Parable of the Sower for apologetics wisdom in what kind of soil you may be dealing with. We're not called to convert; we're called to be faithful.
God can be established and seen through the things we know and through reasonable inferences we can make. However, as our knowledge of reality expands or changes, our views need to realign with the new information. Sometimes that new information is not persuasive. Other times, it is convincing and may offer apparent difficulties for the biblical text. While the Bible is the unchangeable Word of God, our reading, and understanding of the text needs to be somewhat loose. While the Bible doesn't change, we have to allow our interpretations to be somewhat flexible. Either the new information is weak in which case, we can ignore it; it's strong, in which case we have to reassess how we read the portions of Scripture that are at odds with the information. Your zeal for God does not mean the specific views you currently hold and defend are necessarily biblical or accurate. This may sound troubling for some but try to think back into your past and ask yourself this question: did I arrive at all my theological views all at once or was it a process? Process means progress of gaining more and more wisdom/ Gaining wisdom never ends so at the very least give yourself the freedom of the possibility of being wrong. The Bible cannot err; human beings can.
Apologetics can be much broader than the theological truths you're to which you're ultimately trying to win people. If a more general argument ultimately leads a person to eventually embrace the correct narrow theological truth, it can indeed be considered a success. We don't necessarily need to win people to our specific views on secondary issues. By being flexible, we allow a bigger initial gate to allow people to enter. While we must be mindful of what we win people to, by the same token, we should refrain from an all-or-nothing approach, and at least allow people to consider the central claims of the Christian worldview before forcing them down to any narrow secondary view.
What does the victory of apologetics look like? What is the end goal? What is the ultimate effect of success? Think of the person's heart and soul when offering reasons to believe. Remember that what you do is for their benefit, not your own. Remember the end goal - not to win arguments but to win hearts. This can be daunting especially when we think of apologetics as an endeavor of us against them. By its nature alone, perhaps it is unreasonable to keep that mentality away in its entirety, but to whatever extent possible, it's a good idea to keep that in check.
Think of it like this: we're all concerned with truth (we're going to give people who have different beliefs the benefit of the doubt until they prove otherwise). Our aim is to cultivate the truth. We think we have the truth and our counterparts think they have the truth. If we do indeed have the truth, the balance of evidence and reasons to believe so will be weighed in our favor. It is our responsibility to demonstrate this to the best of our ability. Apologetics is a battle between worldviews, not a battle between people.
The Christian worldview paints a particular view of reality as do all other belief systems. The job of the Christian apologist is to demonstrate the truth of the Christian worldview. However, the Christian worldview, as do different worldviews, has central claims. These are the essentials of the belief system without which Christianity could not survive as a reasonable faith. One of these is the resurrection of Christ. As Paul remarks,
"And if Christ has not been raised, your faith is futile; you are still in your sins." (1 Corinthians 15:17)
Ask yourself this: is this worth my time and effort and would a successful outcome bring someone closer to the truth? Is this a make it or break it issue about Christianity? Avoid overreaching and defending secondary and tertiary issues. You can and perhaps on some occasions, should probably defend some of those secondary and tertiary views but demonstrating why abortion is wrong, for example, may not do much to bring people closer to Jesus. A hill I see a lot of apologists live or die on is evolution. Simply pointing out that many progressive creationists have a particular reading of the Book of Genesis that allows for no tension between the Bible and science would go a long way to diffuse the contention. Mind you, I personally don't find purely naturalistic macroevolution to be persuasive, and I take Genesis to be historical, but I avoid that specific debate at all cost as each side has their heels dug in the ground so deeply, that there is virtually no movement on either side. Now and then there might be someone who's convinced from one side to the other, but for all the sparks and drama generated by the friction of debate, there is very little fruit. Discussions on that specific issue can often get so heated that people are no longer interested in reasoning; things can quickly devolve (pun intended) into a grudge match of insults.
Understanding how to reason is perhaps the most important of all the tools in your arsenal. And you don't need to be a world-class philosopher; just learn the basics. Introduction to logic would be one thing to consider learning, and it doesn't have to be technical. Philosophy professor, W. Russell Crawford, has generously provided his Intro to Logic course FREE of charge (see below). Peter Kreeft's Socratic Logic is a good place to start. The second, which dovetails the first is being able to detect fallacious thinking. This ability will do two things, (a) it will help you point out fallacious arguments made by others and (b) help you avoid making fallacious arguments yourself. For this, look into Norman Geisler's, Come Let Us Reason and a very kid-friendly book titled, The Fallacy Detective, that you can even go through as a family.
When you offer reasons for your beliefs, mind the gaps; don't commit the common error of trying to argue from the gaps in our knowledge and offer a God of the gaps. This manner of arguing is problematic. God doesn't merely fill the gaps in human knowledge. He's not just in the domain of the missing puzzle pieces; He's the entire puzzle. While the ancient Greek gods fulfilled that role for the Greeks and Romans, the God of the Bible is not that kind of being; He's a metaphysically necessary being who is over all of reality.
Knowing as much as possible about everything is ideal, but it's unrealistic, especially if, like most people, you have a day job that gets in the way. Generalizing has its place, but given the typical lack of time and energy, it's too difficult in today's world.
Pick a topic that you like, something that you can become knowledgeable about quickly, and specialize. Seek out materials about that specific topic and read more into the arguments therein. Learn as much as you can. When presenting the reasons for your faith, lead with the things you're most comfortable defending, your area of specialty. Not only will you be able to quickly dismiss most of the false views about your area of specialization, but you will likely offer up the most persuasive arguments that you feel most comfortable defending.
I hope these suggestions will help you get started or perfect your pursuit of defending the Christian worldview.