'Full grown' in the Bible

Rejoice, young man, in your childhood, and let your heart be pleasant in the days of your young manhood. And walk in the ways of your heart and in the desires of your eyes, but know that God will bring you into judgment for all these things.

Yet we do speak wisdom among those spiritually mature [believers who have teachable hearts and a greater understanding]; but [it is a higher] wisdom not [the wisdom] of this present age nor of the rulers and leaders of this age, who are passing away;

All of us who are mature [pursuing spiritual perfection] should have this attitude. And if in any respect you have a different attitude, that too God will make clear to you.

We proclaim Him, warning and instructing everyone in all wisdom [that is, with comprehensive insight into the word and purposes of God], so that we may present every person complete in Christ [mature, fully trained, and perfect in Him—the Anointed].

But solid food is for the [spiritually] mature, whose senses are trained by practice to distinguish between what is morally good and what is evil.

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].