Human Reason
Matthew 1:23 Behold, a virgin shall be with child and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us.
Think about it. A virgin. A young girl who had never known a man, carrying a child in her womb. That's a physical impossibility. Can you hear the tongues wagging?
God chose the most unusual sign to mark His divine Son's entrance into the world. Because Jesus had no human father, he had no sin nature.
The miraculous conception of Jesus Christ remains impossible to understand by human reason alone, and God chose not to explain more than He has. Try to understand it and you may lose your mind. Insist on denying it and you will lose your soul.
Human reason can't explain why Jesus didn't call the legion of angles waiting in the shadows to rescue Him from the cross. Human reason can't explain the empty tomb. Human reason can't explain why He died for my sins. But love, grace, and mercy defy human reason. Thank you Lord, for saving my soul.