Here's an idea...
In Malachi's prophecy, God clearly states:
Malachi 4:5
Behold, I will send you Elijah the prophet before the coming of the great and dreadful day of the Lord:
Here, God specifies that He will actually send a specified individual, "Elijah the prophet". And God doesn't lie.
However, John claims not to be Elijah the prophet:
John 1:21
And they asked him, What then? Art thou Elias? And he saith, I am not. Art thou that prophet? And he answered, No.
Yet Jesus turns this around saying that John indeed was expected Elias (Elijah):
Matthew 11:13-15
13 For all the prophets and the law prophesied until John.
14 And if ye will receive it,
this is Elias, which was for to come.
15 He that hath ears to hear, let him hear.
Matthew 17:11-13 King James Version (KJV)
11 And Jesus answered and said unto them, Elias truly shall first come, and restore all things.
12 But I say unto you,
That Elias is come already, and they knew him not, but have done unto him whatsoever they listed. Likewise shall also the Son of man suffer of them.
13
Then the disciples understood that he spake unto them of John the Baptist.
Okay, take this in. God promised specifically to send "Elijah the Prophet". John denies being the coming Elijah. Then Jesus confirms that John was indeed the coming Elijah.
We know that Jesus and God wouldn't lie. So, we'd expect God to actually send "Elijah the Prophet".
And, based on Christ's words, "Elias is come already".
Now, was John lying??? No.
Then why didn't John admit that he was the expected "Elijah the Prophet"?
I propose that John simply didn't know.
You see, man is body, soul, and spirit:
Body: Physical and biological aspect of man
Soul: Psychological aspect of man (reason, will, emotions)
Spirit: Spiritual aspect of man (living essence, intuition, spirituality)
Is it possible that the "spirit" of Elijah was truly present in John? The soul would be different, given John's perspective. As a result, John would not have known that he was Elijah... although he was.
Thoughts?