You were once a citizen of Earth but now, for those in Christ, you are a citizen of Heaven. As the Kingdom of the Earth operates under a "law" and a "way of life," (Which may be subtle as “Do what you want to do”), the Kingdom of Earth also has a law and way of life. We will see in Matthew 5-7 that the new Kingdom has been introduced and Jesus shows us the laws and ways of this Kingdom. As citizens, Jesus invites us to listen and obey his commands. Our entrance, however, is not based on our own good deeds, but on the King's own righteousness.