Now that we have considered verse 1 in a rather full way, let us go on to verse 3. Here Paul says, “Remembering unceasingly your work of faith, and labor of love, and endurance of hope of our Lord Jesus Christ, before our God and Father.” In this verse Paul speaks of three matters: the work of faith, the labor of love, and the endurance of hope. The work of faith comes first. Faith comes through our acceptance of the word that is the embodiment of the Triune God. When we accepted this word, faith was produced within us. We have seen that this faith is both objective and subjective.
In Greek there is a definite article in verse 3, the faith. This indicates that this verse speaks of the work of the faith. This faith is God’s word accepted by us. The word preached to us and received by us becomes faith. Because this faith is living and active, it results in the work of the faith.
The Greek word for work in verse 3 is ergon, a word usually rendered as work. Paul uses this word in Romans 3:20: “Because by the works of law no flesh shall be justified before Him.” In Romans 3:20 work mainly denotes our conduct, our behavior. Paul is saying that no fallen person can be justified before God by his conduct. Thus, in that verse work does not refer to an activity or a task that we do; it refers to particular deeds in our behavior. What, then, is the meaning of work in verse 3? Does it refer to deeds, or to some kind of task? Actually, in Greek this word denotes acts, actions, activities. It includes everything of our actions. Our actions involve deeds, conduct, and many other things as well. Therefore, the work of faith refers to all the acts, actions, of faith.
Suppose an evangelist preaches the gospel to an unbeliever. The unbeliever accepts the word, faith is produced in him, and through this faith he is born of God and put into Christ. Now that he has faith, certain actions are sure to follow. For example, he may spontaneously declare, “O Lord Jesus, You are so precious!” Then he may go home and speak to his wife and children about believing in the Lord Jesus. Both the declaration concerning the Lord and the preaching of the Lord are works of faith. Faith implies God, grace, power, light, and many other items. For this reason, when a new believer preaches Christ to his wife, the faith within him may enlighten him concerning his attitude toward her. Then he will confess his shortcomings to the Lord and apologize to his wife concerning certain matters. This also is a work of faith.
First Thessalonians 1:9 says, “For they themselves report concerning us what manner of entrance we had to you, and how you turned to God from idols to serve a living and true God.” Here Paul speaks of turning to God from idols. This is the first action of faith. Anyone who has faith will turn to God from idols.
The work of faith includes all the actions that issue out of our living faith. This includes our relationship with others and all our behavior. Before a certain person was saved, he may have been unkind to others and harsh in many aspects of his behavior. But once he has faith in the Lord, this faith will not allow him to treat others in such an unkind way. Furthermore, it will be difficult for him to behave in a harsh way. I can testify of this from my experience. From my youth, I hated dogs and sometimes mistreated them. But after I was saved, the faith within me no longer allowed me to behave in that way. Such a change in behavior is an action that comes out of faith.
Those who have faith are very different from those who do not have faith. Before they had faith, some indulged in sinful things. Now that they have faith, they can no longer indulge in these things. Spontaneously, as an action, a work, of faith, they refrain from those things. Others before they were saved were not good neighbors. But after they were saved and came to have faith, they became very kind, gentle, loving, and considerate. No one taught them to be different. The change was produced by the faith within them. The faith caused them to be helpful to others, especially to other believers. This is another illustration of the work of the faith.
The work of faith denotes the proper actions of a genuine believer. It is not the performing of a certain task or the doing of certain good deeds to help others. No, it is our daily action as believers, the action that is a product of faith. This is Paul’s understanding of the work of faith. As he was praying for the Thessalonians, he remembered their action of faith.
Source: http://www.ministrysamples.org/excerpts/THE-WORK-OF-FAITH.HTML