Thank you for posting this Dillinger, I hadn't focused on the language of Matthew 11:12 until now and in re-reading it and the surrounding verses I got a powerful insight that I'd like to share:
Here's the bottom line first, then I'll try to explain how I came to that conclusion:
I believe the soul of John the Baptist was that of Elias. Yes, the Elias of the Old Testment.
Here's my explanation:
Start with what Jesus said in the preceding verse, Matthew 11:11 (KJV) :
"Verily I say unto you, Among them that are born of women there hath not risen a greater than John the Baptist: notwithstanding he that is least in the kingdom of heaven is greater than he."
Now, the last word in this verse, he, is not referring to John the Baptist but rather, them that are born of women.
So, stated another way: The least person in the kingdom of heaven is greater than any person born of women.
That's why the word notwithstanding is there, which kind of means...now take John the Baptist out of the equation for just a second because he is different...or...don't include him in what I say next.
Now come to Matthew 11:14 (KJV) :
"And if ye will receive it, this is Elias, which was for to come"
I believe that Jesus is saying that this is the soul of Elias (from the Old Testament) which was taken from Heaven and placed in the body John the Baptist.
Which gives explanation to the kingdom of heaven suffering violence: Matthew 11:12 (KJV) :
"And from the days of John the Baptist until now the kingdom of heaven suffereth violence, and the violent take it by force."
At the point in time when Jesus said the above verse, John the Baptist had not yet been killed, but he had been taken by violent force and imprisoned having broken no law. I think Jesus knew when He said the above verse that John would be killed but that is beside the point.
As a sidenote, consider the story of Elisabeth, John the Baptist's mother, in the Gospel of Luke (Luke 1:5-80). An angel of the Lord when speaking to Mary, the mother of Jesus, said:
Luke 1:36-37 (KJV) :
"And, behold, thy cousin Elisabeth, she hath also conceived a son in her old age: and this is the sixth month with her, who was called barren. For with God nothing shall be impossible."
Luke 1:41 (KJV) :
"And it came to pass, that, when Elisabeth heard the salutation of Mary, the babe leaped in her womb;"