Elijah was a prophet, a messenger/mouthpiece of God, obedient, zealous for the LORD, a man with interesting attire, and human - so was John the Baptist.
Many believers proceed from step one - Salvation, accepting Jesus as your personal Lord and Savior - to step two - Baptism in the Holy Spirit, receiving God's power for powerful and effective living under His guidance. John the Baptist seemed to have it a little bit better. Luke 1:15 records the angel Gabriel saying, "and he will be filled with the Holy Spirit even from birth." Wow! John gets to pass all "properties" and land on "GO" for a payout right from the start! [Monopoly analogy, ;) ] BUT LOOK THERE'S MORE!
Two verses later in Luke 1:17, the physician describes John in this manner - "And he will go on before the LORD, in the spirit and power of Elijah, to turn the hearts of the fathers to their children and the disobedient to the wisdom of the righteous - to make ready a people prepared for the LORD."
The phrase I want to magnify in this verse is "in the spirit and power of Elijah". What does it mean for John the Baptist to "go on before the LORD, in the spirit and power of Elijah"? It must mean for John to be like Elijah in the same spirit and in the same power. Allow me to elaborate on this and the introductory sentence above.
1 Kings 17 is where we find the prophet Elijah's story begin or at least his name first mentioned. Then throughout the rest of 1 Kings we see Elijah as a prophet. One example of him using this gift or office is found in 1 Kings 21:17-24. Here he prophesied the demise of Ahab and Jezebel. 2 Kings 9:30-37 records the fulfillment of that prophecy. John the Baptist as a prophet can be exemplified in Matthew 3:11-12 - "I baptize you with water for repentance. But after me will come one who is more powerful than I, whose sandals I am not fit to carry. He will baptize you with the Holy Spirit and with fire. His winnowing fork is in his hand, and he will clear his threshing floor, gathering his wheat into the barn and burning up the chaff with unquenchable fire." Some of this has been fulfilled, like the part that says, "after me will come one who is more powerful than I" - that was Jesus. "He will baptize you with Holy Spirit and with fire" - Jesus did that by sending the Holy Spirit at Pentecost. Stay tuned though, Jesus is still to "clear his threshing floor, gather his wheat into the barn and burn up the chaff with unquenchable fire". So, Elijah and John were prophets. They both had the spirit of prophecy upon them and walked in that power.
Elijah was obedient. Just take a look at any of the instructions given to him by God and you will see that Elijah immediately followed them. As an example, in 1 Kings 17:1-5, the LORD instructs Elijah to travel and hide in a certain place where he [God] will provide for him [Elijah]. Verse 5 says, "So he did what the LORD had told him." John the Baptist obeyed God at the Baptism of Jesus. Although reluctant at first, he eventually complied with the LORD's command that this must be done. Matthew 3:13-15 states, "Then Jesus came from Galilee to the Jordan to be baptized by John. But John tried to deter him, saying, "I need to be baptized by you, and do you come to me?" Jesus replied, "Let it be so now; it is proper for us to do this to fulfill all righteousness." Then John consented." So, Elijah and John walked in the spirit and power of obedience.
What an awesome responsibility it is for anybody to be a messenger of God. Elijah was one of the many humans God used to speak through during history, especially Israel's history. According to 1 Kings 21:17, 19 - "Then the word of the LORD came to Elijah the Tishbite...Say to him, 'This is what the LORD says:...'". John's equitable responsibility is documented in Luke 3:4-19. In this passage, which is too long to quote, we have both a prophecy from Isaiah about what John will be proclaiming and then Scripture reports John's words to the different people groups under the power of the Holy Spirit (tax collectors, soldiers, Messiah seekers, and general crowd). So, both Elijah and John answer the call, by the Holy Spirit and in His power, to be God's mouthpiece in their time.
Both Elijah and John were men zealous for the LORD! Elijah shows this in the episode on Mount Carmel (1 Kings 18:16-40). Elijah must have had an extra dose of zealousness because in verses 27-29 he taunts them mercilessly. John's zealousness came in the form of his proclamations too (Luke 3:7-18). One particular declaration concerning Herod and the wife of Herod's brother did not sit well with Herod and John ended up in prison because of it (Luke 3:19-20). So, both Elijah and John were willing, by the spirit and power of God, to go toe-to-toe with the "big boys" of their day for the LORD - Elijah had Ahab and John had Herod.
John must have ordered from the same clothing catalog as Elijah. Mark 1:6 says, "John wore clothing made of camel's hair, with a leather belt around his waist, and he ate locusts and wild honey." Interesting, because 2 Kings 1:8 says about Elijah's attire that he was - "...a man with a garment of hair and with a leather belt around his waist." Somebody might be taking this "spirit of" and "power of" thing a bit too far (haha).
Probably one of my favorite, but not admired, quality in both men was that they were human. Even with the spirit of God and power of God in their lives, they had their moments of weakness. Elijah, after pulling off a bad-to-the-bone, Clint Eastwood-like (with God) showdown against Ahab, beats his foe in a foot race against a chariot that had a sizable lead-time to the city of Jezreel. Then after hearing that Ahab blabbed to Jezebel about being shown-up on top of Mt. Carmel, 1 Kings 19:3 says, "Elijah was afraid and ran for his life." Why? Because Jezebel said, "May the gods deal with me, be it ever so severely, if by this time tomorrow I do not make your life like that of one of them." (v.2) What happened to that confidence in God? What happened to that "spirit of"? What happened to that "power of"? John was human too. His case is one of doubt, especially with the grim circumstances he found himself in - prison. Matthew 11:2-6 says, "When John heard in prison what Christ was doing, he sent his disciples to ask him, "Are you the one who was to come, or should we expect someone else?" Jesus replied, "Go back and report to John what you hear and see: The blind receive sight, the lame walk, those who have leprosy are cured, the deaf hear, the dead are raised, and the good news is preached to the poor. Blessed is the man who does not fall away on account of me." Fear and doubt - two spiritual enemies that when presented to believers, even immediately following a tremendous victory, has potential to steal their joy or "spirit of" or "power of".
So, "the spirit and power of Elijah" that John was endowed with is The Holy Spirit. Within the control of the Spirit, John displays the prophetic gift, the spirit of obedience, usefulness as God's messenger, attitude of intolerance toward unrighteousness or zealousness for the LORD, continues to show our nature and therefore our reliance on God for everything, and even dresses like someone he might have studied and heard about.
For our application, I would recommend that we would use the gift that God has blessed us with individually (talents, skills, etc..). Seek to obey Him at a moment's notice, try not to delay upon hearing His instruction (been here and done this and have the t-shirt). Be open to being used as God's messenger (but screen it through God's Word and His Spirit), if necessary run it by a trusted mentor/pastor first. There are behaviors even within the church that are unrighteous (disrespecting His Name) that we ought to be zealous about, among many other things. Our perspective always needs to be right. It needs to have God as our source that we rely on daily and that we communicate with daily. The dressing alike, well that is a personal call but I tend to go with a more conservative approach now-a-days. ;)