I don't think there's anything that makes living the Christian life more difficult than the fact that the Lord we serve is invisible to us. You know the expression in our culture "Out of sight, out of mind." It's very, very difficult to live your life dedicated to someone or something you cannot see. Often you hear people say that when they can see it, taste it, touch it, or smell it, they'll believe and embrace it, but not before. This is one of the most difficult problems of the Christian life: God is rarely perceived through our physical senses.
On the other side of the coin, I would say that one of the greatest hopes set before the Christian church is the promise of what we call in theology the beatific vision, or the vision of God. We think of John's letter in which he said, "Beloved, now we are children of God; and it has not yet been revealed what we shall be, but we know that when He is revealed, we shall be like Him, for we shall see Him as He is" (1 John 3:2). The Latin there means "as he is in himself." That is to say, that which is totally concealed from our eyes right now, namely the very substance and essence of God, we will see in all of his glory and majesty and splendor in heaven.
I've often wondered about the text that says we will be like him, for we shall see him as he is. Does the Bible teach us that we will be totally cleansed from sin, totally glorified? Is this an experience that will eliminate sin from us altogether? Will it be because we catch a direct glimpse of the majesty of God? For example, if I see him—if he becomes visible to me—is that going to be the cleansing thing that rids all sin from my life; or is my seeing him going to be a result of his first cleansing me? I suspect it's the latter.
Scriptures tell us uniformly that no person shall see God and live; this is because God is holy, and we are not (see Exod. 33:20 and 1 Tim. 6:15). Even Moses, as righteous as he was, pleaded with God on the mountain to let him have an unveiled look at God's glory. God only allowed him to catch a refracted glimpse of God's back parts, but he said to Moses, "My face shall not be seen." Ever since Adam and Eve fell and were driven from the Garden, God has been invisible to human beings, but not because God is intrinsically incapable of being seen. The problem is not with our eyes but with our hearts. In the hymn "Immortal, Invisible, God Only Wise," there is that wonderful phrase "All praise we would render: O help us to see / 'Tis only the splendor of light hideth Thee."
In the Sermon on the Mount, Jesus made the promise that someday a certain group of people would see God. Blessed are those who mourn, for they shall be comforted. Those who hunger and thirst shall be filled. Blessed are the pure in heart, for they shall see God. It's because we're not pure in heart that God remains invisible, and only when we're purified will we see him.