The spiritual maturity of a person is measured by how developed the qualities of the Spirit appear to be within that person, because such qualities can only be grafted in through continuous communion with the Holy Spirit. In the same circumstances people behave differently, because they are filled, cultivated, and instructed by different spiritual sources.
“For the fruit of the Spirit is in all goodness, righteousness, and truth.” (Ephesians 5:9 NKJV)
“But the fruit of the Spirit is love, joy, peace, longsuffering, kindness, goodness, faithfulness, gentleness, self-control…” (Galatians 5:22-23 NKJV)