II Tim. 2:2 You have heard me teach many things that have been confirmed by many reliable witnesses. Teach these great truths to trustworthy people who are able to pass them on to others.
The Gospel message was never meant to be hoarded. We are to learn it well from others and teach it well to others. We know the Gospel is true when we see it at work in others. It's not enough to just hear it preached and taught; we need to see it lived as well. When the two mesh together, we know indeed that it is true and necessary for us to live.
Paul mentions reliable witnesses. It is important that we listen to those whom we know are reliable. We need to be cautious when listening to people we don't know anything about in their personal lives. It is easy to be fooled by what people say so as much as it is possible, strive to discern a person's reliableness before ingesting what they say.
Once we learn what we need to know, we are to in turn pass it on to others who are trustworthy, people who are sincerely wanting to learn the truths of the Gospel. It is not possible for us to know another's heart, but we can usually tell whether or not a person really is interested in learning the truth.
Our goal should always be to keep the flame burning. It is essential for the cause of Christ to instill the Gospel message in each new generation. The more we pass it on, the more people will be brought into the Kingdom of God. Disciples make disciples.