This verse appears in the middle of a longish introductory sentence by which the apostle Paul lays the groundwork for his appeal to the members of the church at Colossae, an appeal that he does not voice until chapter 2. The problem facing this young church in Phrygia was that they were in danger of being "cheat[ed] . . . through philosophy and empty deceit, according to the tradition of men, according to the basic principles of the world, and not according to Christ" (Colossians 2:8). In other words, conditions were such that they were showing signs of believing ungodly ideas promoted by outsiders. As a careful study of the phrase "the basic principles of the world" reveals, these ideas or philosophies had their origins in demons.
As he begins his letter, the apostle wishes to assure the Colossians that word had reached his ears that, despite their vulnerabilities to deception, they were faithful to their calling in Christ and that it was demonstrated in acts of love that they performed to benefit their fellow church members. Thus he lets them know in verse 3 that he always prays for them and thanks God for them. This should have the effect of building their confidence that their election by God was genuine and that they could rely on divine help and strength to face the spiritual battles that they would soon have to wage against these counterfeit doctrines.
Paul had heard of their situation from a reliable source. Verse 7 informs us that one of his proteges, Epaphras, who originally hailed from Colossae (Colossians 4:12), had been working with them and had given him a report of their progress. Evidently, he told the apostle that elements of the local religious milieu were beginning to become apparent in the ideas he was hearing among members of the congregation.
It is not easy to pin down what the exact problem was. Both Jewish and Greek philosophies can be seen in the language Paul uses to describe the problem. There may be some kind of Jewish mysticism, perhaps even radical apocalypticism, present (Colossians 2:18), and certainly, a form of asceticism is mentioned in Colossians 2:21-23. In areas far from the Temple, Jewish philosophers (like Philo in Alexandria) were mixing Judaism with Greek philosophy, creating a strange hybrid of revealed truth and humanistic "wisdom," syncretism of the worst kind since it contains enough truth to attract a believer and enough error to turn his feet off the path to God's Kingdom. These quasi-spiritual ideas later coalesced into formal Gnosticism in the next century, but at this time, the rudiments of such thought were just beginning to take root in various places—one of which was Colossae.
In any case, Paul opens his letter with positivity and encouragement, letting its recipients know that they already have what it takes to stand firm in the faith. If they keep their eyes on the hope set before them, they will endure even this severe trial.