'A lie' is a bit simple. From what I understand, we're all a result of hundreds of years of cultivation and breeding, trained in different ways, to see society and our own place in society in a special context. All our 'significant others' tell us who we are, teachers, parents and people with authority. All this did something to our minds, and led us to a point where we are trained to perceive the world in a certain way. According to the teacher I like to listen to, this is not the natural way. It's something artificial. The purpose of the Buddhist practice, is as I see it, to dissolve this artificiality in behaviour and perception. The end-result is a clear mind, where you see everything without distortion.
I wouldn't say that any of this is a 'lie'. It has lead to the idea of an 'I', which is a very real mental-concept for most people. But according to those who no longer cling to the idea of an 'I', it's a concept you can do without, as it leads to nothing but trouble and suffering. Some call this 'concept' an 'illusion', a 'lie' etc.
As for my take on it. I read and put together ideas from different traditions, and then create my own world-view. Then I discard it the next week, when I read something else. I've been going on like this for the last decade. It's fun to be an amateur-philosopher, but it's not very good zen-practice. Clinging to any mental-concept is a 'no-no' for those who wants to see their own true nature directly, at least when you practice. One places ones 'I' in this world-view that one develops, which makes the concept of 'I' even more complicated and complex. The best practice is just to be completely quiet, and pay attention to the breath, and your surroundings..