New Defender's Study Bible Notes
5:13 useth milk. See I Peter 2:2. Babes in Christ need to feed on the milk of the Word, but they should not always remain babes.
5:14 of full age. “Of full age” is literally “of mature maturity,” essentially the same as “perfection” (Hebrews 6:1).
5:14 senses. “Senses” here means “esthetic senses” (Greek aistheterion), used only this once in the New Testament. It implies a sort of spiritual intuition, by which the sensitive Christian can more or less automatically discern whether something is right or wrong. However, this sense is developed only by attaining real maturity in the Scriptures.