People who identify as Christians but who have no wish to be changed by God, who have no desire to be any different to all the unbelievers around about them - who don't want to live their whole lives for Jesus, who simply don't care much about living in the light and spreading the light of the good news - probably aren't believers. They are maybe God-fearers or people who enjoy the environment and care created by Christians, or people who want a "spiritual bit" in their lives or some kind of divine insurance policy for when they die. But probably they are not believers. And there are loads of them in churches.