You'll notice after some time that your spiritual beliefs and values don't match up as well as you thought, or hoped. The way that your friend tries to expand their consciousness will ultimately seem foreign to you, even if they try their hardest to explain their ideals. In fact, it's the explanation that will seem so strange to you -- the reading and discussing and intellectualizing.
In this relationship, you'll be more apt to rely on gut feelings and intangible cues to form your beliefs. Those beliefs will be difficult to explain to your friend. This may not become a huge issue between you, but since this aspect has to do with your idealistic beliefs and spirituality, you may feel disillusioned with each other once you start to realize that you're not in tandem at that level. But this doesn't have to become a point of contention. If you have a strong communicative bond, you can use this as an opportunity to learn more about the person your friend truly is inside, and vice versa.