Albert Barnes Commentary James 1:4

"And let patience have [its] perfect work, that ye may be perfect and entire, lacking in nothing." — James 1:4 (ASV)

But let patience have her perfect work. Let it be fully developed. Let it produce its appropriate effects without being hindered. Let it not be obstructed in its proper influence on the soul by murmuring, complaining, or rebellion. Patience under trials is suited to produce important effects on the soul, and we are not to hinder them in any way by a perverse spirit or by opposition to the will of God. Everyone who is afflicted should desire that the proper effects of affliction should be produced on their mind, or that there should be produced in their soul precisely the results which their trials are designed to accomplish.

That you may be perfect and entire. The meaning of this is explained in the following phrase—wanting nothing; that is, that there may be nothing lacking to complete your character. There may be the elements of a good character; there may be sound principles, but those principles may not be fully carried out to show what they are. Afflictions, perhaps, more than anything else, will do this; and we should therefore allow them to do all that they are designed to do in developing what is good in us. The idea here is that it is desirable not only to have the elements or principles of piety in the soul, but to have them fully carried out to show what their real tendency and value are. (See Barnes on 1 Peter 1:7).

On the word perfect, as used in the Scriptures, (See Barnes on Job 1:1).

The word rendered entire, (oloklhroi), means whole in every part. (See Barnes on 1 Thessalonians 5:23).

The word occurs only in these two places. The corresponding noun (oloklhrian) occurs in Acts 3:16, rendered perfect soundness.

Wanting nothing. "Being left in nothing;" that is, everything being complete, or fully carried out.