I'm pretty sure I've never said anything about a perfect religion, nor about one that never needs changing. Frankly, I don't think there is such a thing. Certainly no existing religion can credibly claim to qualify for that label.
As near as we can tell, everything changes; change itself seems to be part of the fundamental fabric of the universe. According to the physicists, everything in the universe, down to the last subatomic particle, is in motion, because it possesses at least some kinetic energy. (That makes sense: the "Big Bang" is thought to have been a stupendous release of energy that "cooled" into energetic subatomic particles; all that energy had to go somewhere.) And motion necessarily means change.
We have no reason to think our religions won't need to change. Religions are fundamentally models of the universe and of our place in it. The universe keeps changing, including us. As we learn more about the universe, our models of it necessarily change. When a religion changes because we've learned more about God's creation, it glorifies him, not least because it puts to good use our God-given gifts of memory and reason.