Gandhi was, of course, speaking as an outsider to Christianity, but his observation presents one cold, hard fact that all Christians must eventually confront: There will always be a gap between what we preach and what we practice -- at least in this life.
Indeed, when we are honestly striving to emulate the only perfect Being ever to walk the earth, we are accepting a mortal existence colored by various shades of hypocrisy. This is not a reason to abandon the faith, mind you. The blessings of trying to follow the commandments far outweigh the immediate sting of repentance. And, in the end, isn't it better to fall short in the pursuit of greatness than to shun greatness altogether?