Savagewind,
Witnesses do not teach that Jesus has come, but that he is going to come again very shortly. The Bible tells us to keep on the watch for his coming, Matt 24:42,44.
Even though the second coming of Jesus has not happened yet, it is very close, as the world conditions prove, beyond any doubt. In Matthew chapt 24, Mark 13, and Luke 21, many of the signs that Jesus' disciples asked him about at Matthew 24:3, which are the many signs of Jesus coming.
2Timothy 4:1-5, these say that people will not listen to truth, but will gather preachers together to teach them what they want to hear.
Titus 1:16, says that people say they know God, but their works prove they are lying.
Jesus taught that only truth was acceptable to God, John 4:23,24, Paul taught the same, 2Thessalonians 2:9-13, Ps 145:18.
According to all the signs that Jesus told us to look for, Jesus is near, at the door, Luke 21:31,32.
Don't wait until it is too late, Luke 21:25-28. If a person has not learned before Jesus comes again, let will be too late, 2Thessalonians 1:6-9.