Nothing will tarnish your testimony more than engaging in back-stabbing gossip and slander with co-workers. I recall one of my husband’s assignments to minister at a church–we had just been hired and were having lunch with the staff. The pastor could not come with us so for the entire meal we listened to the staff members talk about their pastor. It was the most uncomfortable experience I’ve had.
My husband and I could not get up and leave because we had ridden with some of those attending so we were at their mercy. However, after a while of complete silence from both of us it finally dawned on them what was happening. They changed the subject and we finished our meal. I tell you though, the damage was done. We felt detached from this group of people for the first few years of our ministry at that location. It took a long time for them to gain our trust.
A word of advice, don’t gossip! It affects the people you talk about, but it also affects those around you and your image and testimony. Most of all, it brings shame to the gospel of Christ.