Christians are proud of how Jesus' birth was foretold in the Old Testament. Here's the full quote:
Therefore the Lord himself will give you a sign: behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel. Butter (or curds) and honey shall he eat, when he knoweth to refuse the evil, and choose the good. For before the child shall know to refuse the evil, and choose the good, the land whose two kings thou abhorrest shall be forsaken. - Isaiah 7:14-17
There is some confusion as to whether the mother is a "young woman" (Isaiah) or a "virgin" (Matthew), so the intact state of her hymen was not unambiguously foretold. Regardless, the prophecy is wrong, if applied to Jesus. The prophecy is about the birth of a child named Immanuel, and that he would eat curds and honey when he knows how to choose good and refuse evil. Before this was to happen, the land belonging to two kings (Ahaz and Rezin) was to have been deserted. The lands were Judah and Syria, and they have never been deserted. There is no reference anywhere in the New Testament about Jesus eating any curds and honey. Finally, it is not a part of the Christian philosophy that Jesus had to learn how to choose good and refuse evil.
So, the cornerstone prophecy of Chirstianity is wrong on several counts.