John was sent as one of three witnesses to God's work through the Christ (the others being God the Father and God the Holy Spirit) who testified at Jesus baptism. John the Baptist drew attention to Jesus. He was clearly a well known person in his day drawing huge crowds. His opinion mattered too - even to the ruler Herod who was so bothered by John's opinion that he had him killed-clearly he carried some influence.
We as Christians also need to testify as to who Jesus is as everyone needs to know Him to be made right with God. I struggle to do this effectively as I feel people have a real prejudice against Christ today. But then I also think I could be bolder.
John was killed because of his position and opinion of Herod. He had this position and his convictions because of who he was and what his job was. It is unlikely I would be killed if I testified clearly - though I would definitely be challenged, probably ridiculed and ultimately shunned by many in mainstream society. The people I testify to however could meet Jesus and be saved.