The trustworthy man is the witness who does not lie or bend the truth. He is dependable and reliable. What he says he will do. There is also the reliability of what he says - when he says it - it is the truth. In Jesus' day some religious hypocrites would say that it was fine to bend or misrepresent the truth - unless you were swearing to tell the truth - or basing your statement on some oath you made to speak the truth. To Jesus this was totally unacceptable. He said, "Let your yes be yes and your no, no." Your word is your bond. This is the attitude of the trusthworthy witness. Jesus said that anything beyond your word being your bond is of the evil one. This may sound a little harsh - but to couch anything in lies - and to make your word something other than the truth is satanic. The trusthworthy man WILL NOT LIE!
It seems simple - but the false witness utters lies. We are not used to such blunt talk in our day of bending and stretching the truth. We are used to things like spin and qualified statements. Such is the world we live in where truth lies fallen in the streets - especially in the streets of Washington D. C. There is much that the Bible says about a culture that has tossed truth to the side. It will be a difficult world to live in - one fraught with troubles. That is why speaking the truth is important. That is why God put this one in the 10 Commandments - "Thou shall not bear false witness."
This becomes even more important when sharing the way of salvation. When we become witnesses to the gospel - we need to speak the truth, the whole truth, and nothing but the truth. Too often in our day we have genius' who have decided that we can package the gospel in a way that is less offensive and that will garner greater receptivity. There is a word for those who practice this kind of foolishness - false witnesses. We need to share the gospel just as it is - as good news! But we cannot hide the sinfulness of man - or the work of the law in condemning sinners before a holy God and still be a truthful witness. We cannot take the Lordship of Jesus Christ and repentance and lay them aside because they lower our success rates - and still call ourselves God's witnesses. These things are nothing more than lies.
One thing we should remember when sharing the gospel - and honestly - when sharing anything. Truth may hurt - it may offend - but it is the only thing that will set men free. To share anything else is simply putting ourselves in the camp of those who are false witnesses. Some may say that if we do this - we won't see as many people saved. My answer to them is that it is the ONLY way to see people saved. Salvation is God's work - not ours. If we do not speak His truth - and trust Him to open a man's heart, granting repentance and faith in Jesus Christ - no one will be saved. Be a truthful witness. Refuse to lie - no matter the issue. In time men will come to know you as one who speaks the truth . . . and they will trust you. The other option here is out of the question.