James 1:4

And let patience have its perfect work, that ye may be perfect and entire, lacking in nothing.

That ye may be perfect ... It is a gross error to read "perfect" as used in the New Testament as if it meant "maturity." This is exactly the word that Jesus Christ our Lord used of the heavenly Father himself (Matthew 5:48), where Christ commanded, "Be ye therefore perfect as your heavenly Father is perfect." Nothing short of absolute perfection shall ever inherit eternal life; and, while it is freely admitted that no man may achieve such perfection, it is nevertheless available to all men who will receive the gospel, be baptized into Christ, and thus become partakers of the heavenly perfection of the Saviour himself. See the dissertation on "The Perfection of Christians" in my Commentary on Galatians, Ephesians, Philippians, and Colossians, pp. 120-124. This is the theme of the whole epistle of James, all of its various instructions fitting into the category of what is required for perfection. Implicit in the admonitions of this epistle is that Christians must do their very best to achieve whatever degree of perfection is possible, whatever is lacking to be made up by Christ himself (and there will always be something lacking in every Christian). Dummelow and many others insist upon reading "perfect and entire" as "full grown and complete";[14] but it would be impossible to speak of God as "full grown"! The meaning here is "perfection," which is exactly what the text says. It is believed that the reason why so many are unwilling to accept this obvious meaning lies in their failure to understand how the total perfection of Christ becomes the inheritance of all who are truly "in Christ." See Colossians 1:28. It is certain that James understood this; and his entire letter is directed to the admonition that the Christian should not presume that Christ's perfection would be bestowed upon Christians who trusted a subjective trust/faith alone to procure such a status, or who might fail in any manner of doing everything within their power to honor "the perfection in Christ" through their constant imitation of it. The testing of the Christian's faith by various external trials, as in this verse and the preceding verse, carries the inherent message that the Christian must pass such tests. If in his sincerely trying to do so, the Christian should nevertheless fail, Christ in that extremity will surely provide what is lacking.