First, I believe developing spiritual senses takes self-discipline. Paul says in 1 Timothy 4:17 to "train yourself for godliness". The word train is gymnazo in the Greek, so he is talking about some kind of exercise or hard work. What kind? If you look at the life of early Christians they fasted, they prayed, they studied scripture, the hung out together and what was the result? They walked with God to the point that they changed the world.
A couple of things I realized about these things though - first they are NOT the point (or the evidence) of Christianity. The point is to walk with God, and these things are only means to that end. In other words, what difference does it make if you have some tough spiritual regimen if it makes no impact on the rest of your life? Secondly, and I cannot stress how important I think this is, what works for someone else may not work for you. I seriously cannot do a food fast. I am a big guy with a high metabolism, so when I don't get enough calories I get tired and moody - which sort of defeats the purpose I think. Then there is personal taste too. Some people like (for example) "high church" liturgies and find great benefit in them, other people think they are the dullest thing ever. That's okay. God made us different and allows us to relate to Him differently (within Biblical guidelines of course).
If you've ever been frustrated (as I certainly have) by trying to follow someone else's advice as to how to pray, how to hear God's voice, etc I highly recommend a book called Sacred Pathways, by Gary Thomas. He profiles people in the Bible and how they related to God in different ways, and then suggests that each of us are wired in different ways and we need to figure out our own spiritual temperament and try to build our spiritual disciplines around that. The book is so helpful and practical. It even has a quiz to help you discover your own spiritual temperament and build your spiritual activities around that. One of the best half-dozen or so books I've ever read.
Now I'm going to go out on a limb a bit-but I think God gave us our physical senses as gateways to our spiritual ones. Romans 1 says that which may be known about God has been made evident in creation. But if that's so, why do so few people see Him there? Probably because they don't look. Most anyone who has been to Albuquerque (where I live) will tell you that the most striking feature of the city (besides about 8 trillion tons of sand) is the mountain range that forms the city's eastern border. The peak is something like 6,000 feet above the city (I'm too lazy to look up the actual height) and you can see it from almost anywhere. It's actually quite nice, b/c when you're lost you can always look up and see which way is east.
With my natural eyes I see the mountains the same way everyone else does - rocks, trees, snow at times, and that amazing pink hue at sunset. But I am learning to see more than that. For example, I see a reminder of God's righteousness (Psalm 36:6). Like the mountain, His righteousness never changes, never moves, and can withstand any and every storm. Or I can be reminded that even a problem as big as the a mountain is nothing for a person with faith. But how and why can I be reminded of that? Because I've taken the time to get the Word into me (spiritual discipline), and because I am learning to look for God's truth in natural things.
Think how often Jesus spoke of natural things to explain spiritual. Then He often said something like "he who has ears, let him hear" or even criticized people for not getting it. I think maybe He wasn't just teaching whatever the point of His parable was, but He was also teaching us to "hear" or "see" spiritual truth in natural things. I know there is a danger in that (we can misread natural things) and that's why we to be full of His Word, talk to Him throughout the day, and stay connected to others who can tell us if our ideas are completely off the wall.
This is where a really great blogger has some powerful final thought that ties it all together. I don't. I appreciate your thoughts and comments though - tell me if I'm completely off the wall!
I think next week I'll ramble a bit about faith.