All verses like this and Matthew 5:28 (where Jesus talks
about adultery in a similarly
harsh manner, are meant to do is point us straight to verses of Paul's such as Romans 3:23 and Ephesians 2:8 - 9: it's the evidence Jesus provides that, no matter what, even if we never murder a single person or in any way commit adultery, we're nothing without Him... and, oh, yeah, it's the meter that shows us who we are and why we need Him, and only Him (John 14:6), to get to heaven.