The strongest Christian argument to an atheist is not usually "just believe," but a cumulative case: God exists, Jesus was a real prophet-like figure, and the resurrection is the best explanation of the early Christian movement. That case deserves a fair hearing, but it proves less than many Christians think.
How the Christian case is put at its strongest
A serious Christian apologist normally begins with God before beginning with the Church. He may argue from the beginning of the universe, the order of nature, moral truth, consciousness, and religious experience that atheism is too small to explain reality.
Then he moves to Jesus: that Jesus of Nazareth existed, taught with unusual authority, was crucified, and that his followers very early claimed he had risen. He may cite the sincerity of the disciples, the conversion of Paul, the willingness of early Christians to suffer, and passages like 1 Corinthians 15 as evidence that the resurrection belief was not a late legend.
The argument is then: if God exists, miracles are possible; if the resurrection happened, God vindicated Jesus; if Jesus was vindicated, Christianity is true.
Where the argument is strongest
Against a hard atheist, the first part has real force. Theism is not irrational. A created, ordered, morally meaningful universe fits belief in God better than blind matter alone. Islam agrees fully that belief in the Creator is natural, rational, and deeply rooted in the human being.
Were they created by nothing, or were they themselves the creators? Or did they create the heavens and the earth? Rather, they are not certain.
Quran 52:35-36
The historical point also deserves respect. Muslims do not treat Jesus as a myth. We believe he was the Messiah, born miraculously to Mary, a mighty messenger of God, supported by miracles. So a Muslim can honestly say: much of the Christian case against atheism is closer to Islam than to atheism.
Where it overreaches
The leap comes when "Jesus is special" becomes "Jesus is God," or when "God acted for Jesus" becomes "the Trinity, incarnation, and atoning crucifixion are true." Historical arguments alone cannot carry all that weight.
Even if an atheist granted that the disciples sincerely believed they had seen Jesus alive, that would not automatically establish Nicene Christianity. It would establish, at most, that something extraordinary lies behind early Christian faith. The interpretation of that event still has to be argued.
Islam gives a different reading: Jesus was not divine, and worship belongs to God alone. The Quran honors Jesus while rejecting exaggeration about him.
O People of the Scripture, do not commit excess in your religion or say about Allah except the truth. The Messiah, Jesus, the son of Mary, was only a messenger of Allah and His word which He directed to Mary and a soul from Him. So believe in Allah and His messengers. And do not say, "Three"; desist - it is better for you.
Quran 4:171
This is the key difference. Miracles do not make a prophet into God. Adam had no father or mother, yet he is not divine. Moses split the sea by God's permission, yet he is not divine. Jesus gave life to the dead by God's permission, yet he remains the servant and messenger of God.
What it really establishes
Plainly: the Christian argument can establish that atheism is not the only rational option, that belief in God is intellectually serious, and that Jesus cannot be dismissed as insignificant. It may even persuade some people that early Christianity was built on sincere testimony, not deliberate fraud.
But it does not, by itself, prove the Trinity, the incarnation, inherited sin, or salvation through the crucifixion. Those doctrines need clear revelation, not only historical inference. From the Islamic view, the final and preserved revelation confirms Jesus and corrects later claims made about him.
So the fairest answer is this: the best Christian case is a strong argument against atheistic reductionism, but it is not a decisive proof of Christianity's full creed. It opens the door to God; it does not force the conclusion that God became a man.