Ephesians 5: 1 & 2
Verses one and two give us instruction on how we are to walk as Christians. Paul begins the chapter with two commands:
1) Be imitators of God
2) Walk in love
While these seem overwhelming at times, notice the way in which Paul presented them--both as behaviors modeled to us. In verse one, he reminds us that we are beloved children of God. Often, children pick up their parents mannerisms just by being in the same house with them. My mom and I haven't lived in the same house for almost ten years, and yet when we're together, I laugh at how much I already act like her. Paul is evoking the same natural reaction here. As children of God, we ought to act like God.
The second command, to walk in love, is also a modeled behavior for us. He tells us that we're to love others with the same love that we've been shown. If ever there was a perfect model for love or a perfect reminder of what love looks like--it's Jesus at the cross; it's his sacrifice for our sins; it's giving himself in order to give us a relationship with God again. Paul is reminding us that we've already been modeled the best behavior of love, and we've been loved with an everlasting love, despite our undeservedness. Therefore, we ought to know how to walk in love, as Christ did, because we have the perfect reminder of love living inside us.
I think the "catch" is that to really imitate someone, you have to know them. Not just on the outside, but from the inside. You have to know what they are like, how they move, what they would do in a given situation, how they respond to adversity and success. You have to know their heart. And you can't know God without having an intimate relationship with Him. I believe the same is true for modeling Christ's love. When you fully experience the fullness of Christ's love and sacrifice, then it becomes an outward response and expression to others. You begin to walk humbly, knowing the gift you've been given, and you walk with grace because of His grace toward you. If you only know Jesus' love in part, or through logic, or just as facts of salvation, you'll never be able to effectively respond to Him or to others in love. Modeling Chris's love, as Paul commands here, is a learned behavior, developed from a revelation of who Jesus is and how much He loves you. Only with that hidden in our hearts can we take the first steps of walking in love.