In his greeting to the Colossians Paul mentions two details about them: they were holy and they were faithful brothers. What does he mean by these descriptions?
The term saints means holy or separated ones. There are two ways by which this description can be explained, one by an outward sign and the other by an inner reality. The outward sign of profession is baptism and this ritual does depict the washing away of sins; the inward sign of possession is the indwelling presence of the Holy Spirit. I suspect that Paul hoped that each of the Colossians would both profess and possess.
We are prone to minimise the significance of baptism. Yet we should not do so, because it was the door of entrance to the visible church. In baptism, we are identifying ourselves with the people of God – it is the sign that we belong to the community of Jesus. Of course, it is possible to only go through the outward ritual and not possess the indwelling of the Spirit. Baptism nevertheless is a permanent reminder to live in dependence on God.
The other detail that Paul mentions about the Colossians is that they are faithful brothers. Paul reminds his readers of the great privilege of adoption as he speaks directly to them. He addresses them as faithful. No doubt he means those who are loyal to God. But how do they show their loyalty to God? The main way is by how they interact with one another. Faithfulness to God is always revealed in how we regard the church of God.
It is possible to use the word ‘believing’ instead of ‘faithful’. If we use ‘believing’, it does not imply that faithfulness is not intended. Instead ‘believing’ indicates how we can continue to be faithful and loyal. Everything a Christian does, everything a church does, must be done by faith in Christ. There will be dependence on Christ and devotion to Christ.