In 1 Corinthians Paul addresses the saints in Corinth – “To the church of God that is in Corinth, to those sanctified in Christ Jesus, called to be saints…” (1 Cor 1:2 ESV). He speaks to the entire church but later he calls some ‘babes” and some “spiritual” saints.
“…in the church of Christ there are two classes of Christians: (1) Those who have lived many years as believers and yet always remain babes; (2) Those who are spiritual men because they have given themselves up to the power and the leading of the Holy Spirit…” Andrew Murray (ref#272, p8).
“The SPIRITUAL were those who, after conversion, had continued to grow in the grace and knowledge of the Lord, no longer continuing as ‘babes in Christ.’” James Burton Coffman (ref#298). Babes “were in Christ, and so were new creatures…though babes and weaklings in it” John Gill (ref#300). Babes were carnal “…those who were continuing to live like the unconverted…” James Burton Coffman (ref#298).
“But I, brothers, could not address you as spiritual people, but as people of the flesh, as infants in Christ.…For while there is jealously and strife among you, are you not of the flesh and behaving only in a human way” (1 Cor 3:1,3 ESV)?
Backsliders: “Turn, O backsliding children, saith the LORD; for I am married unto you:…” (Jer 3:14 KJV). “…we do not speak of the destruction of the root principle in your soul, but of the decline of its power…” Octavius Winslow (ref#135, Aug 22nd).
The terms “backslider,” “people of the flesh,” “carnal,” “babes” can depict a Christian (a not-advancing Christian) or a non-Christian since no one but GOD knows the condition of the heart, but in 1 Corinthians, the Apostle Paul uses these terms to address Christians.