Not all of us are called to preach publicly, but all of us are called on to play our part in spreading the Gospel - the "Good News" that Jesus Christ is God with us, that he died to reconcile us to the Father, and that he is risen from the dead and has poured out the Holy Spirit on his chosen ones.
There are many ways we can do this and many different words and examples we can use to get this message across to the world around us. First of all, as fellow believers we remind each other of the good news by talking about our faith together, by encouraging each other to grow in knowledge of our faith and by praying together.
Sometimes we may need to explain some point of the Church's teaching to a fellow Catholic or clear up a misunderstanding. This can happen in casual conversation through ordinary friendships or in a formal setting like a school governors group, and so on. To "counsel the doubtful" is one of the spiritual works of mercy.
We may be called on to catechise others in the Church, such as children and young people or adults seeking full communion with Christ. This is both an honour and a duty. We are co-workers of the apostles (bishops and priests) in this work, but as lay Catholics we are all equipped and commissioned to speak for Jesus Christ because of our baptism and confirmation.
We should always be alert to situations where a Christian influence can be brought to bear on the world around us. Of course it is best not to do this in a sanctimonious or "churchy" way. But if we have built genuine relationships of trust and respect, and offered honest friendship to those around us, then with the help of the Holy Spirit, we will find the right words to say when the opportunity arises. It may be a matter of dropping a thought provoking comment into a conversation which helps people to see beyond the secular view. Or it may be that we quietly invite someone to a spiritual event or gathering, introducing them to the Catholic community - and ultimately introducing them to Jesus Christ.
There may also be times when we are called on to speak up in public or private situations where misunderstandings or misconceptions about the Catholic faith are being repeated. We may have to bear witness to human moral principles which are being undermined in politics, writing to the press or lobbying parliament. We have to use our skills and influence in the world to protect the common good and promote an authentic Christian society.