A manger - And this shall be a sign unto you

"And this shall be a sign unto you; Ye shall find the babe wrapped in swaddling clothes, lying in a manger". - Luke 2:12

What is the manger a sign of?

Isaiah saw a vision concerning Judah and Jerusalem.

"Hear, O heavens, and give ear, O earth: for the LORD hath spoken, I have nourished and brought up children, and they have rebelled against me." - Isaiah 1:2 KJV

Another word for "manger" is "crib."

"The ox knoweth his owner, and the ass his master's crib: but Israel doth not know, my people doth not consider". Isaiah 1:3

God gave Isaiah a vision of His coming. While the ox and donkey recognize their master, Israel did not recognize their God that cared for them. The manger was a sign.

"He was in the world, and the world was made by him, and the world knew him not. He came unto his own, and his own received him not.

God came to bring salvation.

"Come now, and let us reason together, saith the LORD: though your sins be as scarlet, they shall be as white as snow; though they be red like crimson, they shall be as wool." - Isaiah 1:18 KJV (Isaiah 1:19-20).

God came in the form of man so that He could shed blood for our redemption. He came to pay the price that only He could pay – sinless blood – to pay for our sins.

"But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name: which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God". - John 1:10-13

Those that receive Jesus, believing that He is God - Creator and Savior – are able to be born again of water and of the Spirit to have our sins washed away. Though our sins were scarlet, by the blood of Jesus and by His name, they are white as snow. By the power of His Spirit, the Holy Ghost, we are able to keep victory over sin. (Acts 17:2, Acts 18:4, Acts 24:25).  

This is what Peter preached on the Day of Pentecost.

"Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost. For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call." - Acts 2:38-39 KJV