He walked among them and they knew Him not.

The Jews missed their Messiah (Jesus Christ). He walked among them and they did not recognize him, even though their prophets described His coming in great detail.

Brethren, my heart's desire and prayer to God for Israel is, that they might be saved. For I bear them record that they have a zeal of God, but not according to knowledge. For they being ignorant of God's righteousness, and going about to establish their own righteousness, have submitted themselves unto the righteousness of God. For Christ is the end of the law for righteousness to every one that believeth. For Moses describeth the righteousness which is of the law, That the man which doeth those things shall live by them. But the righteousness which is of faith speaketh on this wise, Say not in thine heart, Who shall ascend into heaven? (that is, to bring Christ down from above:) Or Who shall descend into the deep? (that is, to bring Christ again from the dead.)

But what saith it? The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith, which we preach; That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation. For the scripture saith, Whosoever believeth on him shall not be ashamed. For there is no difference between the Jew and the Greek: for the same Lord over all is rich unto all that call upon him. For whosoever shall call upon the name of the shall be saved.

(Romans 10: 1-13)