First John 3:2b and 1 John 4:17b are at different places in the timeline of salvation history.
A TIME YET FUTURE
The former speaks of a future time when both Christ's true identity and believers' true identity will be revealed. Because the believers in the apostle John's time were plagued by false christs (i.e., the antichrists spoken of in 2:18), they looked forward to the time yet future when they would not only see Jesus as he is, but they would also be like him and would be recognized and loved by God because of the "family resemblance."
In the apostle John's day, being like Jesus made Christians an unknown entity in the eyes of the world. Once in Christ's presence, however, who Christ really is and who they really are would be made plain. When Jesus revealed himself to his fellow Jews during his earthly ministry, he was neither recognized nor received as God's Christ:
The true light that gives light to everyone was coming into the world. He was in the world, and though the world was made through him, the world did not recognize him. He came to that which was his own, but his own did not receive him.
In the yet-future glorified state, however, there will be complete recognition and acceptance of Christ as he really is by those who are like him: Brothers and sisters in Christ.
IN THE PRESENT TIME
The latter passage speaks of the present for Christians both then and now. In their dealings with the world, Christians of any age are to model Jesus's love to each other and to unbelievers. Like Jesus, they will often be misunderstood, persecuted, and rejected, but love will ultimately triumph at Jesus's parousia.
Yes, there are times when Christians behave badly. They fail to manifest the love of God to one another and to unbelievers. With regard to our actions in loving our fellow brothers and sisters in Christ, we all fall short of living a life of love. The perfecting process to which John refers in 4:17b is part of the sanctification process in which all Christians take part. Some Christians are further along in that process than others, and God's existential timetable for each Christian will differ.
Nevertheless, believers' standing in Christ is not jeopardized by their occasional lapses of not living and abiding in God's love. Believers' growth in love may be sporadic and gradual, but that growth is a reason for giving them confidence in the day of judgment (see 2 Corinthians 5:10). Jesus lived a life of love, with no lapses and no failures, but that did not prevent him from being arrested, tried, and crucified.
Christians today can expect to experience misunderstanding, impugned motives, and hatred at the hands of unbelievers, yet the rewards for living a life of love are great. There can be no exaltation without initial humiliation. That was true of Jesus, and it is true for his true believers as well.
Who, being in very nature God,
did not consider equality with God
something to be used to his own advantage;
rather, he made himself nothing
by taking the very nature of a servant,
being made in human likeness.
And being found in appearance as a man,
he humbled himself
by becoming obedient to death—
even death on a cross!
Therefore God exalted him to the highest place
and gave him the name that is above every name,
that at the name of Jesus every knee should bow,
in heaven and on earth and under the earth,
and every tongue acknowledge that Jesus Christ is Lord,
to the glory of God the Father.
