You know, Peter was quite sure about Who Jesus was. Even though he denied Him three times in one night, he knew beyond a shadow of any doubt exactly Who Jesus was. As a matter of fact, Jesus knew that he knew exactly Who He was, testifying and grounding Peter in the fact that it was God the Father Who had revealed Jesus' true identity to Him through personal revelation knowledge (Matthew 16: 16-17) .
Peter knew Who Jesus was. After all, he was there at Jesus' transfiguration on that mountain – seeing with his own physical eyes the Lord's glory revealed, and hearing with his own hot little ears the Almighty God's voice announcing His personal approval of Jesus, when He declared, "This is my beloved Son, in whom I am well pleased; [take heed and listen to] Him "(Matthew 17: 5). Other than Jesus Himself – along with the possible exception of Mary His Mother (Luke 1: 28-35) – no one else on earth could have been more sure about Jesus' identity and nature than His distinguish Peter. That that's why Matthew 10: 2 calls Peter the 'first' – that is, the 'chief' – apostle (because in mere 'order of selection' Andrew, Peter's brother, actually came to follow Jesus before Peter did [John 1:35 41]. But, I digress …
Here's an issue we're probably all familiar with: You're trying your best to believe the Lord for something, or you unfortunately need His wisdom in a matter. You're struggling maybeily, feeling around for the right direction to go, but you're just not sure which of the thoughts you're having is the 'right' one – or if any of them are, for that matter. In short, you do not have a clue what to do, and God does not seem like He's in that much of a hurry to give you any concrete answers. Finally, in some combination of confusion, dismay, exhaustion and, yes, even irritation, you cry out, "Lord, please; if You could just give me some kind of sign here! Can not you see that I'm struggling, and that I'm looking to You for help ?? "
I assure you, He sees it. But, vastly unbeknownst to us, the fact of the matter is that even if the Lord relented andave us a big red flashing sign with an arrow pointing in the appropriate direction, that's still no guarantee we'd actually believe it enough to act on it. We could find our brains 'rationalizing' us right out of what our natural senses had experienced. (Of course, this would actually be Satan whispering to us to disregard God's leading, trying his best to either 'talk us out of' or 'into' something.)
The Apostle Peter came to realize this truth, and we as apostles (yes, we're all apostles also – we've all been 'sent' into the world as Christ's Ambassadors for the Kingdom of God [2 Corinthians 5:20; Mark 16:15]) must become aware of it, as well. Peter taught that, even though he saw and heard of the Messiah's glory with his very eyes and ears, even though he himself was there and had firsthand knowledge of Jesus' majesty; when push came to shove, he did not rely on any 'sights' or 'sounds' he received through his physical senses. He relied on something even more stable and trustworthy: the 'written down' Word of God! (2 Peter 1: 16-19)
Now, I'm not saying that God will never, ever give us any types of signs. I'm not saying that at all, because He certainly will – when He deems it appropriate. After all, He's in the miracle-working business – always has been, always will be; because He does not change (Malachi 3: 6). And, signs can be big, hugely conspicuous events that nobody can miss; or they can be very small, quiet, inconspicuous "coincidences" that nobody sees – except you (because you're the one it's for … and because of the fact that there's no such thing as a 'coincidence'). But, signs are generally not for believing Christians; they're a great mean to show unbelievers that there really is a God behind the scenes doing work (1 Corinthians 14:22). Believing Christians are supposedly to (indeed, we're commanded to) live not by our eyes, ears or by signs, but by our faith in God's Word (Isaiah 11: 3; 2 Corinthians 10: 7; Romans 1:17; John; 1: 1).
The point here is that forty-eight hours after you received a 'sign,' you could be asking all over the place just what it was your eyes saw, and why they saw it. But, forty-eight hours after, God's written Word is going to say the same thing it said forty-eight hours before – or forty-eight years before, or forty-eight centuries (Hebrews 13: 8). That's what Peter meant when he called the Holy Scriptures a "more sure [stable, firm, steadfast, trustworthy] word of prophecy" (2 Peter 1:19), and we're much better off to put our ultimate faith and trust in them than in anything else. All of God's Word is profitable for teaching, convicting, correcting and directing us (2 Timothy 3:16). His Word should be the first place we look to, and it should be "The Last Word" for every question and decision we need to make in our lives (Revelation 1:11, 22:13).