What does Eph 5:1 mean when it exhorts us, “Follow God’s example, therefore, as dearly loved children” (NIV)? Should we try to be omnipresent (everywhere at once), as God is? Should we try to create the universe? The context is very specific how we should imitate God. We should forgive as God in Christ forgave us (4:32) and love one another, just as Christ sacrificially loved us (5:2).
Paul similarly invites his hearers in Corinth to imitate him as he imitates Christ (1 Cor 11:1). Paul offered himself in 1 Cor 9 as an example of giving up his rights; in 10:33, he summarizes, “just as I try to please everyone in everything I do, not seeking my own advantage, but that of many, so that they may be saved” (NRSV). This is how Paul followed the example of Christ, and invites others to follow his example.
Other passages also speak of imitating God or Christ, although in different words. For example, 1 Pet 1:14-16 urges us not to act like we did before we followed Christ, but to be holy in our behavior as God is holy. That is, God has set us apart for himself, so we should behave like those who are consecrated for God’s eternal purposes, not living for things that do not really matter. (Peter cites Lev 11:44-45, where God already invited this imitation, in that case by Old Testament food customs separating Israel from surrounding cultures.)
In Matthew 5:48, Jesus calls us to be perfect as our heavenly Father is. This does not mean that if we miss a point on a test we are disobeying this command. The context is God’s example: he sends the agricultural blessings of sunshine and rain on both those who serve him and those who do not. In the same way, we should love our enemies, thus acting like his children who follow his example (Matt 5:44-45). (This is clear in the same context in Luke, where Jesus is instead quoted as, “Be merciful, just as your Father is merciful”; Luke 6:36 NASB.)
Something goes even deeper than imitation, however, and enables us to imitate God in these moral ways. If we recognize Jesus as our Lord and Savior, he sends God’s Spirit to live in us (Rom 8:9). The fruit of God’s Spirit in us means that God’s own character, his own heart, is at work inside us. Because of this, we will grow to be more and more like him, because of his own gift of his Spirit to us. (For more detail on this, see the post on this website concerning the fruit of the Spirit: http://www.craigkeener.com/the-fruit-of-the-spirit-galatians-522-23/.)