Back when I used to listen to Christian radio, I heard this song that drove me crazy. It goes like this:
I've seen dreams that move the mountains
Hope that doesn't ever end
Even when the sky is falling
I've seen miracles just happen
Silent prayers get answered
Broken hearts become brand new
That's what faith can do
Now I think understand the sentiment behind songs like these. However well intended, the lyrics are quite absurd because faith has no power apart from its object! Faith is like an extension cord. It has no power in itself. You can plug it into a carboard box or a bowl of mashed potatoes if you want to. But you’ll get no power unless its plugged into a working electrical outlet.
So too with faith. It’s power comes in its object. If your faith is rooted in something unreliable or untrue, it’s worthless. Faith only has power if its plugged into something trustworthy and true. Is your faith like an unplugged extension cord? Or is it rooted in something? Better yet, is it rooted in Someone?
The story of Joseph’s adoption of Jesus teaches us a great deal about Jesus, the object of our faith. Consider these three truths:
He is Truly God
Matthew 1:18—...When His mother Mary had been betrothed to Joseph, before they came together she was found to be with child from the Holy Spirit.
Mary’s pregnancy is unlike any other in human history. She is pregnant, but not by Joseph. Russell Moore puts it this way: “Joseph was not Jesus’s biological father; not a trace of Joseph’s sperm was involved in the formation of the embryo Christ. No amount of Joseph’s DNA could be found in the dried blood of Jesus peeled from the wood of Golgotha’s cross. Jesus was conceived by the Holy Spirit completely apart from the will or exertion of any man.” 
And it’s not only Joseph’s DNA that’s absent. No man was involved in the conception of this baby. Mary’s been pure, she’s a virgin. But she has a child growing in her womb. Matthew sees this virgin conception as evidence that Jesus is truly God.
Matthew 1:22-23—All this took place to fulfill what the Lord had spoken by the prophet: “Behold, the virgin shall conceive and bear a son, and they shall call His name Immanuel” (which means, God with us).
He is Truly Man
Matthew 1:18—...Mary … was found to be with child...
Mary was not pregnant with an alien or some sort of freak of nature. She carried a child within her. Contrary to most of the famous paintings of Mary and the Christ child, Jesus wasn’t born with a halo or with a creepy man-face. The Christmas song is absolutely wrong when it says, “The little Lord Jesus, no crying He makes.” Jesus was truly human. He was born a bed-wetting, milk drinking, crying, cooing, baby boy.
When he walked the earth, nobody doubted that Jesus was human. It was His divine nature that was hard to accept.
Matthew 13:54-56—And coming to His hometown He taught them in their synagogue, so that they were astonished, and said, “Where did this man get this wisdom and these mighty works? Is not this the carpenter’s son? Is not His mother called Mary? And are not His brothers James and Joseph and Simon and Judas? And are not all His sisters with us? Where then did this man get all these things?”
These verses completely bust a myth taught by the Roman Catholic church, that Mary was a perpetual virgin. Jesus had brothers and sisters! These verses also demonstrate that Jesus looked like an ordinary guy to most people. He was truly man.
He is the Savior
Matthew 1:21—"She will bear a Son, and you shall call His name Jesus, for He will save His people from their sins.”
How will Jesus save His people from their sins? The Scripture our clear, He saves us by dying in our place. Matthew 20:28 says, The Son of Man came not to be served but to serve, and to give His life as a ransom for many.
Why must our Savior be truly God? Only God can live without sin. Only God can bear the righteous anger of God for all our sin. Only God can rise from the dead.
Why must our Savior be truly man? Only a man can be tempted, yet live fully obedient to God’s law. Only a man can suffer and die.
What’s your faith connected to? Is it an unplugged extension cord? Or is it plugged into something or someone that has no power? Is your faith in science? Government? Work? The economy? Yourself? Put your faith in Jesus! He’ll never let you down.
Russell Moore, Adopted for Life: The Priority of Adoption for Christian Families and Churches, Updated and Expanded Edition (Wheaton: Crossway, 2015), 60.