Witnesses reveal what someone has done. For example when someone does a bad thing and you saw it, that means you were a witness that the person did the do that bad thing.
Answer:
It was considered a threat because the Church considered having the knowledge of the Bible as a privilege reserved for the clergy. They felt it would reduce their status among general public if they were translated into the language of the common man. Also they feared that heretical teachings or misinterpretations occurring while transcribing.
Lincoln was trying to appeal to Southern voters by picking Andrew Johnson as his running mate. These two men were actually very different politically speaking. Lincoln was a Republican, Andrew Johnson was a Democrat. Lincoln was from the Midwest US, Andrew Johnson was from Tennessee.
Lincoln knew that having a Democratic Vice President who once represented a Confederate state (Tennessee) would allow his presidency to appeal to a wider range of voters.
