Ideally, Soly, you should do both.
I don't know about you two, but I find my heart is not the easiest thing to listen to. It's small, it's selfish, and it's continually changing. That "dumb old book" broadens it; makes me look past myself and my own silly prejudices; gives my heart words that I can latch onto. And it's such a wonder to listen to my heart and find that, across the millenia separating us, someone else's heart has resonated with mine. Those thousands of years are the book's very strength and beauty. Those years allow us to share the wisdom and the heartache and the joy of people who laughed and loved as we do - could we concede that the rest of humanity might have gotten something right? Or do we prefer to make all the same mistakes, and relearn all the same lessons, over, and over, and over, out of some perverse pride in doing it all by ourselves? We mess up enough even knowing the consequences ahead of time.
If you've never experienced the Church as a community, I don't blame you for thinking it's dispensable for your personal salvation. Because the formal structure of it certainly is dispensable.
The people are not. How are you going to learn to love and to forgive others, and to be forgiven, if you're never around them? How are you going to be effective at doing any good in this world, if you're too self-absorbed to look for help? It's just a matter of practical sense to know that 2, or 10, or 200 people working together are going to feed more children and shelter more refugees than you all by your lonesome. And how do you expect to learn anything true about God on your own? Wouldn't you just be worshiping the product of your own imagination? If God is real, you're not going to have exclusive access to him. Like it or not, other people's ideas about him may be just as valid as yours, and need to be taken into account. You have a right to think those other people are wrong and to argue why, but you can't ignore what they have to say. That would be religious bigotry, my friends, and of the worst order.
Finally, you're not doing the same thing when you're by yourself as when you're with another person or persons - and that goes for every activity. To use an analogy we'll all understand, it's like NS. You can play NationStates all by yourself, answering the issues you get sent and never bothering to join the UN or reply to telegrams. Or you can come someplace like Taijitu, and get on the forums, and find a whole different level to what was supposedly a simplistic game. That's the difference between going it on your own and being part of something bigger than just you... and believe me, you still have to listen to your heart either way.