As Christians, our mission is to proclaim the Good News.
We proclaim the Good News in whatever state of life we are in.
So it may be by preaching and teaching, or in witnessing by what we do at work, or in whatever service we provide for others.
The core of this Good News is summed up concisely by St. Paul in the 1st reading as he said this:
We have come with Good News to make you turn from these empty idols to the living God who made heaven and earth and the sea and all that these hold.
That is the Good News that we bring to others so that they will come to believe in God and be saved.
But others will only believe when they can see that we ourselves are living out the Good News of salvation.
So the Good News must make its home in us. That also means that God has made His home in us.
When God has made His home in us, then our words and our actions will be from the One who is living in us.
When God is living in us, then the Good News will just flow from us to others.