We are not given many details about events leading to John the Baptist's murder yet enough is said to show that this miracle child of Zechariah and Elizabeth was the greatest of all the prophets up to that time. He was born to fulfil the ancient prophecy about a messenger who would come to prepare the way of the promised Messiah - Jesus Christ (Malachi 3:1-2). John was born a few months before Mary's miracle child was born, and John died a gruesome death a very few years before Jesus died a far more gruesome death. He pointed to Jesus Christ as the Light, and that the only way to see that divine Light was to repent and be baptised. Then such repentant ones would be prepared to receive Jesus Christ by faith. John was the forerunner to the Christ; and he died for the Christ, whose very foot-latches he felt unworthy to handle.
Now, that is the question - did he really die for Christ? The idea presented is that "he did not die for refusing to renounce his religion, nor did he suffer for witnessing to Jesus... it seems that John the Baptist died for the political offense of publicly criticizing the ruler." Well, how many thousands of Christians have been executed by political and religious powers for publicly offending the ruler by disobeying their laws that violated God's laws? Their executioners rarely said they were killed for being Christians (apart from recent decapitations etc. of men in orange boiler-suits). Usually, they are charged with breaking some laws of the land (or of the church, as in dark ages in the past).
Merriam-Webster's definition could really do with an update. Especially by dropping the 'voluntary' bit. Those captured, lined up and beheaded or shot - did they 'voluntarily' submit to that? What does the Bible say about John the Baptist and his wicked murder?
John came to bear witness to the Light, John 1:7, that all through him might be saved. Salvation. "The true light is over there," John effectively said, pointing to Jesus Christ. "Repent and be baptized" he said. Those who did were then prepared to follow that Light because then their hearts had been touched and the good seed of the kingdom would take root therein. To as many as receive Christ, to them he gives power to become the sons of God. Salvation in Christ alone. That startling witness echoes down the centuries to this day. All who proclaim it are Christians.
Yes, John the Baptist's preaching was from heaven, a fact Jesus challenged the religious leaders of his day with - Mat.21:25. Yes, John bore witness to Christ - John 3:26. Yes, he frankly rebuked the ruler for his immorality and was then imprisoned. But did that rule out the two other clear indicators that he was the first follower of Christ at the time of Christ - in other words, a Christian? And that he was murdered for not recanting the biblical truth he had stated or for not paying a bribe to Herod - does that mean he could not be a martyr for the Christian faith? John preached publicly in order to get people prepared for salvation in Christ. That he fell foul of a political ruler by condemning sexual immorality in the court does not negate his Christianity. Or, are we becoming so conditioned by today's fluid standards of sexuality, that we won't say "Boo!" to a "goose" on that front even though Christians are to be sexually pure, even in their thoughts? Do those claiming to be Christians today think biblical requirements for Christian conduct have no part to play in witnessing for God and Christ? John's example exposes hypocrisy, and if one has to die for speaking plainly, then so be it.
In Mark's gospel (chapter 1) John preached the baptism of repentance unto [eis] the remission of sins. He preached of Christ coming after him, mightier than him. In his ministry, John challenged behaviour of all who heard him, long before he challenged Herod. Sins were exposed; sins were to be admitted; sins were to be confessed. Herod had his sins exposed by John; Herod did not deny his sin but neither did he admit it; Herod never confessed his sin. (Mark 6:14-29) To quote:
"Eventually, Herod decided to please Herodias who had attempted to
kill John for his words, but could not, Herod being, apparently, so
keen to observe, hear and hear gladly, the man who had told him what
was not lawful. But time, and life, and circumstances, worked together
to expose the heart, as they always will. And Herod's true evaluation
of the man he seemed so diligent to hear, and observe and hear again,
gladly, was to be seen by all men...
But Herod desired to please his - unlawful - woman, rather than to
hearken to the messenger sent of God to prepare the way of the Lord...
How did Herod value [John]? Less than the opinion of them that sat
there and less than half of his kingdom... How shall we value the
messenger who prepares the way of the Lord? Do we not realise that,
without him and his words, we shall never see the Lord?
Herod's fearing; Herod's hearing; Herod's observing; were all,
utterly, worthless. For Herod did not repent. He was preoccupied with
pleasing others - his unlawful woman and those who sat to watch a
damsel dance.
Later, he killed the apostle James, John's brother, with the sword and
saw that it pleased the Jews. So he proceeded to take Peter also.
After Peter's release by angelic means, Herod ascended a throne and
was lauded as a god by the crown. Had he but spake the words in
denial, he would have been spared. But he loved the praise of men and
judgment fell upon him... But Herod never wanted to please the One for
whom John was sent to prepare the way. For Herod never repented." The
Beginning of the Gospel, pp. 30-33, Nigel Johnstone, Belmont
Publications, 2012
Why would Herod's murders of James and Peter cause them to be called 'martyrs' but not that of John the Baptist? Consider Revelation 6:9-11 as the final word on the matter:
"I saw under [heaven's] altar the souls of them that were slain for
the word of God and for the testimony which they held. And they cried
with loud voice, saying, How long, O Lord, holy and true, dost thou
not judge and avenge our blood on them that dwell on the earth? And
white robes were given unto every one of them; and it was said unto
them, that they should rest yet for a little season, until their
fellow-servants also and their brethren, that should be killed as they
were, should be fulfilled." (A.V.)
John the Baptist was slain for the word of God, and for the testimony which he held fast to. He is in their number, he really died for Christ. That is the definition of a martyr that the Bible gives us.