Hebrews 3:1

"Therefore, holy brothers, who share in the heavenly calling, fix your thoughts on Jesus, the apostle and high priest Whom we confess."

This may seem like a preacher's transition phrase. However, if you want a good one-liner about the book of Hebrews, I think you have it here.

The writer has just finished in chapter 2 telling us that Christ named us as his holy brothers: see verse 11. God brought us to glory; Jesus wrote our salvation.
There's no more heavenly calling than this!
Then the author concludes his however: "fix your thoughts on Jesus." This is what his lesson is about. It started with Jesus in Hebrews 1:2 and it concludes with Him in 13:15 and 21.
Jesus is the apostle sent by God--this the author has been telling us since chapter 1. ("in these last days He has spoken to us by His Son..." 1:2)
Jesus is also the high priest appointed by God. This is what the author is about to get into.

Watch the word therefore in the book of Hebrews. It occurs 16 times in 13 chapters; it seems to be the author's favorite transition word. It builds up from the first chapter, a prophetic quote applied to Jesus: "You have loved righteousness and hated wickedness; therefore God, Your God, has set You above Your companions by anointing You with the oil of joy," and goes on to the final therefor in chapter 13: "Through Jesus, therefore, let us continually offer to God a sacrifice of praise--the fruit of lips that openly profess His name."

Maybe we should foster some therefore in our lives today... How often do you go through the day, reacting to the day as it unfolds? Do you sometimes find yourself "just getting by" through the day? It happens to me a lot.
But the book of Hebrews is all about the greater therefore: the Impetus to which we should be reacting every moment of every day. God created us, therefore we should praise Him--but He didn't stop there. God saved us in His Son Jesus Christ.
God saved me today through Jesus Christ. What will my therefore be?

Hebrews 2:15ff

And so, the greatest irony of salvation is that we have been saved, not by an all-powerful, omnipotent being, but by a normal human being. We can't look on the face of God or we shall surely die--but men looked on the face of Jesus and saw another guy, just like themselves...
This is the wonder of all creation: the Right Hand of Creation came down and became an average human--and it was in the truest sense of the word, for He came not as a human king but as a normal blue-collar worker. The steel worker walking the girders at your downtown construction site does not look much different than did the man Jesus, for that was His niche in life.
God, you see, had the idea of everyman down long before our playwrights. Jesus Christ was a perfect, noble, righteous man as no other, but He was a man we could look at, a man we can follow, a man Who understands us and our needs and our weaknesses. We understand the difficulties He faced as He understands ours.

It is to be His brethren that we are called, to be made in His likeness. When people look at us, as we grow in the Spirit and in Christ, they will see the resemblance between us and Him. This is as it should be!
My sisters look a lot like me. I look like my mother and father, who look like their brothers and sisters. There's a family resemblance, and when I go back to their hometowns, I tell people my family name and they say, that's right! You look just like them!
So if we are called to be the family of God in Christ, the same rule applies: when I introduce myself to someone in Maine or Los Angeles or Cairo and I tell them to Whom I'm related, they should look at me and say, yes, you're right! I can see the resemblance!
It's funny, that. How does a Russian Christian look? A Japanese Christian? A Brazilian Christian? An African Christian? In so many respects, these people are so different--and yet, having lived their lives for One man, having been born into one Word and with one baptism, these people can worship God together as one. It's truly inspiring.

What's the end of this matter? Jesus! Consider Jesus, the man Who "did not consider equality with God a thing to be grasped, but made Himself nothing, taking the form of a servant, being made in human likeness." (Philippians 2:6-7) He is our model and saviour, the Lover of our souls, the Righteous One, the only Son of God. And He is our brother.

Hebrews 2:14

"Him who holds the power of death." God?

Funny, no. "Him who holds the power of death" in this passage is Satan.
Satan is the father of death, no? It was he that tempted the woman in the garden; it was on his account that man fell. So as God is the father of life, Satan is the father of death.
So it is in all things: God fathers life, Satan fathers death from life. God fathers love, Satan fathers lust from love. God fathers need and desire, Satan fathers envy, jealousy, and all manner of evil ambition. Satan does not create evil from nothing; he is not a Creator. He merely twists the things God has made.
As we are made by God, so was Satan. We are free to make our own choices; so was he. We are free to use God's creation to our own creative ends; so is he.
Satan is not the one with the power of death because it is something he created or innovated. He has the power of death because he is the cause of death; he drove men to death at the beginning, and he does so now. He wants death for you, and he wants death for me, because he chose the evil instead of the good.

God gives us that choice. Through Jesus Christ, Who took on our humanity for us, we have the choice to become righteous. It's a hard road, and it's not a quick one; but it is a journey He will make with us.
God made us to need: we need food to survive. We need water for our bodies to function. We need companionship to stimulate our minds and to keep us grounded in reality. But we need more than this. We need purpose, we need meaning. We need for there to be a reason we're here. Scientists find that reason in science, but we find our reason in God.
How do we fulfill that need? Can we find that fulfillment in oaken pews or in golden crosses? Is it in wooden statues built by men?
God has given us the means to experience closeness with Him, and it's not in cults or in rituals or in icons or in the world around and the sky above. Our means to learn of God, to be with God, is in the Word of God--He has given us no better means by which we can determine His innate attributes or His glory, and He has given us no other way to realize His wishes for us.
It is by the Word that we know Jesus Christ, by the Spirit and from the Word that we learn of God, by our knowledge and faith in the Word that we discern and follow what is good.

How can a young man keep his way pure?
By living according to Your word.
I seek You with all my heart;
Do not let me stray from Your commands.
I have hidden Your word in my heart
That I might not sin against You.
Praise be to You, O LORD;
Teach me Your decrees.
With my lips I recount
All the laws that come from Your mouth.
I rejoice in following Your statutes
As one rejoices in great riches.
I meditate on Your precepts
And consider Your ways.
I delight in Your decrees;
I will not neglect Your word.
-Psalm 119:9-16

May this be my prayer and yours all the days of our (young) lives!