When dealing with atheists, it's almost unavoidable that your motives, intellect, or even morality will be called into question. Large numbers of atheistic arguments involve some kind of attack on the person, rather than the case being made. "You're only a Christian because you were raised to be Christian". "You want it to be true, so the evidence you're presenting is just confirmation bias on your part." "You lack the relevant qualifications." The most ridiculous example I've seen to date is an atheist attacking Lee Strobel, an ex-atheist who found Christ in his attempts to disprove the Christian faith. Apparently, his wife must have just threatened not to let him back in her temple unless he converted too... (the atheist's words, not mine).
All of these arguments, and more, commit the same basic fallacy: Ad hominem. Ad hominem literally means "to the man", and as the name suggests, the flaw in the argument is that rather than criticising a belief or argument on its actual merits, it basically calls some part of the believer into question.
This doesn't work, for obvious reasons. Objective truth exists independently of human beings. You can swap out human beings, or remove them entirely, and the truth claim still has equal value. A NASA scientist cannot tell a 3 year old that the world is flat and have it suddenly become true.
It also often commits the genetic fallacy: The criticism of a belief or argument based on its perceived origins. Suppose it was true that I somehow came to believe the Christian faith entirely because of my English environment. Would that somehow invalidate the Christian faith? Consider the simple fact that I also know about germ theory only because I was raised in a country where public school is free. Had I been born to some impoverished community in a third world country where only the rich have access to a quality education, I might never know of these tiny organisms that could potentially threaten my health if I don't take adequate measures to control them.
Now, note how 4 paragraphs into an article about the strength of the Christian faith, I have yet to actually discuss it. This whole time, rather than show any evidence for the faith, I have instead had to explain some of the most basic logical fallacies a man can make. Anyone who has taken a critical thinking course will be able to identify the problems in these common atheistic arguments, yet even popular atheistic apologists with fancy degrees continue to make these mistakes. This, I believe, is actually the goal. See, when people are set aside, and the Christian faith is examined on its own merits, Christianity tends to come out on top. It is so much easier to dismiss Christians as a bunch of uneducated, superstitious, suspiciously motivated quacks, than to actually deal with the case we have.
Of course, some people are more relevant than others. How can you assess whether Jesus was actually the Son of God if you ignore Jesus? Or the people who wrote about Him? Realistically, this is impossible. However, it's worth noting that not everyone who wrote about Jesus lived during His time. One of the most powerful evidences for Christianity is the prophetic word strongly confirmed.
Throughout the Old Testament, many prophecies of Jesus can be found, so much so that to fulfill even a handful of them by chance is as statistically likely as guessing your PIN on the first try. To even list these prophecies, much less explain how Jesus fulfilled them, would literally take an article as long as the New Testament (which is precisely why the New Testament exists). However, for now, let's examine my personal favorite: Isaiah 53.
"Who has believed our report? And to whom has the arm of the Lord been revealed? For He shall grow up before Him as a tender plant, And as a root out of dry ground. He has no form or comeliness; And when we see Him, There is no beauty that we should desire Him. He is despised and rejected by men, A Man of sorrows and acquainted with grief. And we hid, as it were, our faces from Him; He was despised, and we did not esteem Him. Surely He has borne our griefs And carried our sorrows; Yet we esteemed Him stricken, Smitten by God, and afflicted.
But He was wounded for our transgressions, He was bruised for our iniquities; The chastisement for our peace was upon Him, And by His stripes we are healed. All we like sheep have gone astray; We have turned, every one, to his own way; And the Lord has laid on Him the iniquity of us all. He was oppressed and He was afflicted, Yet He opened not His mouth; He was led as a lamb to the slaughter, And as a sheep before its shearers is silent, So He opened not His mouth. He was taken from prison and from judgment, And who will declare His generation?
For He was cut off from the land of the living; For the transgressions of My people He was stricken. And they made His grave with the wicked— But with the rich at His death, Because He had done no violence, Nor was any deceit in His mouth. Yet it pleased the Lord to bruise Him; He has put Him to grief. When You make His soul an offering for sin, He shall see His seed, He shall prolong His days, And the pleasure of the Lord shall prosper in His hand. He shall see the labor of His soul, and be satisfied. By His knowledge My righteous Servant shall justify many, For He shall bear their iniquities. Therefore I will divide Him a portion with the great, And He shall divide the spoil with the strong, Because He poured out His soul unto death, And He was numbered with the transgressors, And He bore the sin of many, And made intercession for the transgressors."
Upon reading this, especially without the knowledge of its origins, most people automatically identify this as a description of Jesus. This includes Jews, whose book it comes from. Isaiah is a Jewish prophet, and his book remains a part of the Tanakh to this day.
Of course, there are a number of ways people try to get around this, starting with the simple fact in most translations, this prophecy is cited in past tense. However, any Hebrew grammarian will tell you this is not a problem. See, unlike in English, wherein we have past, present, and future tenses, classical Hebrew only has two: Perfect, and Imperfect.
Perfect denotes a "completed action", which may be past, present, or future. We actually have a similar concept in English, such as when we tell someone "you're a dead man". In classical Hebrew, the Perfect is often used in prophetic language, especially by God Himself, who "...calls those things which do not exist as though they did;..." (Romans 4:17), when an event that is yet future is being spoken of as though it were as good as done.
The Gospel has been the most sure truth since before the world even began (e.g. Titus 1:2). Thus, Isaiah 53 is not some mere possibility. God isn't saying "if you're lucky, I might provide a substitute for your iniquity". No, this is the most certain fact that ever was. Therefore, 700 years before the birth, death, and resurrection of Christ, it was entirely appropriate for the same God who told Abraham "I have made you the father of many nations" to deliver this prophecy in the Perfect, which can be accurately rendered in the English past tense.
What's more is that while modern Jews, and those who mimic their kicking against the goads, will tell you Isaiah 53 refers to Israel rather than the Messiah, this is not the opinion of the Rabbis of the past. I could list a great many examples, but the simplest and most easily recognisable would be the Babylonian Talmud. Sanhedrin 98b reads, regarding the Messiah's name, "And the Rabbis say: The leper of the house of Rabbi Yehuda HaNasi is his name, as it is stated: “Indeed our illnesses he did bear and our pains he endured; yet we did esteem him injured, stricken by God, and afflicted”"
Although the Bible refers to "the Remnant", i.e. Jews who readily acknowledge Jesus as the Messiah, the majority of them do not, and have not. Hence the modern reinterpretation that Isaiah 53 refers to Israel. However, this example, and many others, show that this was not the case even after Christ's resurrection. Isaiah 53 was always understood to be a Messianic promise, not a past tense reference to Israel.
And no one's modern opinion affects that.
You can accuse any Christian today of being deluded, brainwashed, insane, even wicked, but you cannot erase the fact that Jesus easily fits the description of the promised Messiah in the Old Testament. Many details, from the major to the minor, were foretold hundreds of years before His birth. Even the very place of His birth: Bethlehem, this unassuming little town with minimal respect from the masses. And this is just the beginning. The evidence for the Christian faith is as extensive as the time since Christ ascended into Heaven and sat down at the right hand of the Father until His enemies are made His footstool.
And so, my atheist friends, I have good news, and I have bad news. The bad news is, as it stands, you are on track to become that footstool. Because of your endless rebellion, you are owed nothing but His wrath. But the good news is, His word tells us He takes no pleasure in the death of the wicked (Ezekiel 18:32; 33:11). It is not His will that you perish (2 Peter 3:9), but that you should be saved, and come to the knowledge of the truth (1 Timothy 2:3-4). Therefore, while He is still providing breath for your lungs, you are able to escape your ultimate demise. Repent, and confess Jesus as Lord, believing in your heart God raised Him from the dead. It is the one who rejects such a fantastic offer whose psychology should be questioned.