Contradiction with Hebrews 5:14
This verse suggests that strong meat is for those who are mature, contradicting the idea in 1 Corinthians 3:1, where Paul refers to the Corinthians as babes in Christ, only able to consume milk.
Hebrews 5:14: But strong meat belongeth to them that are of full age, [even] those who by reason of use have their senses exercised to discern both good and evil. [of full age: or, perfect] [use: or, an habit, or, perfection]
Contradiction with 1 Corinthians 14:20
This verse encourages believers to not be children in understanding, which contradicts with 1 Corinthians 3:1, where the Corinthians are described as immature in Christ.
1 Corinthians 14:20: Brethren, be not children in understanding: howbeit in malice be ye children, but in understanding be men. [men: Gr. perfect, or, of a ripe age]