People in physical need also have spiritual needs. Integral human development demands attention not only to the food and water people need, but also their spiritual wellbeing. The proclamation of the hopeful message of the Gospel is the best way to help people spiritually.
Every Christian, however imperfect, is called to give witness of their faith (Mk 16:15). You do so in the first place by simply trying to live as a good Christian. Only when you live in accordance with your faith, will your words be credible. There are many places where priests and nuns cannot go. We need all Christians to join in with our task to live the faith and proclaim the Gospel through our lives. That way you can evangelise through your profession too.