If we had been in a courtroom or at least seen courtroom dramas on tv  and movies, then we may know what it means to be a witness.
To  stand as a witness means that one is most likely to be cross-examined,  or grilled, either by the prosecution or by the defense attorneys.
To be a witness, there are two necessary elements: to know the truth, and to speak the truth.
Jesus calls us to be His witnesses.
To  be His witnesses, there are two necessary elements: to know Jesus and  His teachings, and also to have a deep relationship with Him.
It is from this knowledge and relationship that we witness to Jesus with our words and actions.
We witness to Jesus in a world that may not know who Jesus is, and to a world that thinks it can do without God.
In a world that is filled with hostility and disregard for human dignity, our witnessing to Jesus is vital and necessary.
 --Rev. Fr. Yim -Homily for 5/30/2011