What does it mean to be "in Christ"?

For 2017, the phrase I am focusing on is "in Christ."  Each week, I will post 1 verse that includes the phrase "in Christ". I look forward to growing in understanding of what it means to be "in Christ."

¹⁰ We are fools for Christ's sake, but you are wise in Christ. We are weak, but you are strong. You are held in honor, but we in disrepute. ¹¹ To the present hour we hunger and thirst, we are poorly dressed and buffeted and homeless, ¹² and we labor, working with our own hands. When reviled, we bless; when persecuted, we endure; ¹³ when slandered, we entreat. We have become, and are still, like the scum of the world, the refuse of all things.¹⁴ I do not write these things to make you ashamed, but to admonish you as my beloved children. ¹⁵ For though you have countless guides in Christ, you do not have many fathers. For I became your father in Christ Jesus through the gospel. ¹⁶ I urge you, then, be imitators of me. ¹⁷ That is why I sent you Timothy, my beloved and faithful child in the Lord, to remind you of my ways in Christ, as I teach them everywhere in every church.  (1 Corinthians 4:10-17)