The bottom line is this: looking beyond all of your false assurance, religious activity, or fair exchanges, do you live with a desire for obedience to the Word of God? Is that the goal you're striving for--not for the perfection of your life (which comes only in heaven)? And when you disobey it, as we all do daily, do you have a sense of conviction and remorse that draws you to confess it to God? If that isn't there, it's a fair question whether you're a Christian.