'Perfection' in the Bible

In this [union and fellowship with Him], love is completed and perfected with us, so that we may have confidence in the day of judgment [with assurance and boldness to face Him]; because as He is, so are we in this world.

There is no fear in love [dread does not exist]. But perfect (complete, full-grown) love drives out fear, because fear involves [the expectation of divine] punishment, so the one who is afraid [of God’s judgment] is not perfected in love [has not grown into a sufficient understanding of God’s love].