The previous verses in Philippians said that Christians should cultivate their salvation because God is working in all of them. Paul then told them particularly what they should do: they should not grumble at each other.
14 Do all things without grumbling or disputing;
15 that you may prove yourselves to be blameless and innocent, children of God above reproach in the midst of a crooked and perverse generation, among whom you appear as lights (like the Sun and the Moon) in the world, (Phil 2:14-15)
Like plants give off oxygen, so the world gives off grumbling and disputing. That’s the norm in business and in family life. A very clear way of showing God is at work in the lives of Christians is to stop grumbling and complaining about each other. If we do that, it is a miracle. And miracles always draw attention to themselves. Paul even went on to say that we would stand out like the Sun and the Moon over the Earth. So how do we cultivate our salvation as a group? We harmoniously work with one another and don't grumble and complain at each other.
