"I thank my God always when I remember you in my prayers, because I hear of your love and of the faith that you have toward the Lord Jesus and for all the saints..."
Philemon 1:4-5 ESV
God uses and works through all of His children. In the above verse, Paul shows that he thanks God for how loving and faithful Philemon is towards both the Lord and the brethren.
When reading through the New Testament, Paul is often opens his Epistles with a statement of thankfulness to God.
A couple of examples are below.
"First, I thank my God through Jesus Christ for all of you, because your faith is proclaimed in all the world."
Romans 1:8 ESV
"I give thanks to my God always for you because of the grace of God that was given you in Christ Jesus, that in every way you were enriched in him in all speech and all knowledge..."
1 Corinthians 1:4-5 ESV
"We give thanks to God always for all of you, constantly mentioning you in our prayers, remembering before our God and Father your work of faith and labor of love and steadfastness of hope in our Lord Jesus Christ."
1 Thessalonians 1:2-3 ESV
Let us follow Paul's example and be thankful to God about our brothers and sisters in Christ. Often, there are countless flaws in all Christians, however nonetheless, let us be thankful about those that have also been given the duty and honor to advance the kingdom of God and give Him glory.