First Q: In Matthew 17:10, Jesus says that John the Baptist was Elijah. But John the Baptist denies being Elijah in John 1:21. Arent these two statements irreconcilable?

A: No; see the comments at Matthew 11:14 - Was John the Baptist Elijah?

Second Q: So, was John the Baptist Elijah?

A: John the Baptist was an anti-type to Elijah, resembling him and his work in various ways, and this is what is meant when Jesus says that John was Elijah. But John the Baptist and Elijah the Tishbite were not the same individual; the assumption that they were identical is what John denies in John 1:21. Similarly, one could say that Jesus is the "scapegoat" in the sense that He fulfills some elements in the typological pattern of the "scapegoat" in the Old Testament, while denying that he is identical to the scapegoat.

Third Q: In Matthew 17:11, Jesus says that Elijah truly shall first come, and restore all things. If John the Baptist is in the role of Elijah, what did he restore?

A: Jesus may not be referring to John the Baptist until 17:11; the reference in 17:11 may be to an individual in the future (possibly one of the Two Witnesses described in Revelation 11) who will set the stage for the Second Coming. In that case, the gist of Matthew 17:11-12 is that while the Elijah-pattern will be fulfilled in the last days, theres more to it than just that future scenario; John the Baptist also filled Elijahs silhouette.

If, though, 17:11 /is/ referring to John the Baptist as Elijah, then Jesus probably used the term restored the way we would use the term straightened up, like a house-cleaner getting a house ready for an honored visitor; the idea would be that John the Baptist got everything ready for the ministry and mission of Jesus.

Yours in Christ,

Waterrock