Relationships are the playing field where our faith is put into action. All the behaviors that Paul strongly urges the Colossians to avoid (anger, slander, etc) are ones that are relational in nature. Likewise, the behaviors he calls them to (love, forgiveness, etc) can only be lived out in relationship. God uses all kinds of relationships; healthy relationships, challenging relationships, providential relationships to help us grow in our faith. Relationships are not an obstacle to faith; they are the fertile soil in which faith grows.