"And I, brethren, could not speak unto you as unto spiritual, but as unto carnal, even as unto babes in Christ. I have fed you with milk, and not with meat: for hitherto ye were not able to bear it, neither yet now are ye able." (1 Corinthians 3:1-2)

The apostle Paul here makes a clear distinction between "spiritual" Christians, controlled and led by the Holy Spirit, and "carnal" Christians, still controlled by the desires of the flesh. A carnal Christian is a baby Christian. Baby Christians are a cause of great rejoicing when they are newborn believers, just like baby people. But if they remain babies indefinitely, they become an annoyance to hear and a tragedy to behold.

Each born-again believer needs urgently to "grow in grace, and in the knowledge of our Lord and Saviour Jesus Christ" (2 Peter 3:18). That spiritual growth comes only through study of the Word, accompanied by belief and obedience. First there must be "the sincere |or 'logical'| milk of the word" (1 Peter 2:2), but that is good only for the first stages of growth. "For every one that useth milk is unskillful in the word of righteousness:
for he is a babe. 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" (Hebrews 5:13-14). Scripture encourages us to grow to maturity and then to continue growing.

Carnal Christians are not necessarily pseudo-Christians, although they should examine themselves to determine whether their profession of faith in Christ is genuine (2 Corinthians 13:5), but they should not be content to remain spiritual babes. Every Christian should be able to say with the prophet Jeremiah: "Thy words were found, and I did eat them; and thy word was unto me the joy and rejoicing of mine heart: for I am called by thy name, O LORD God of hosts" (Jeremiah 15:16). HMM http://www.icr.org/article/6072/