People use the word "Christian" to mean all sorts of things — a background, a culture, a rough moral outlook. In the Bible it means something more specific and more personal: someone who has come to trust Jesus Christ, and who is learning to follow him.
That starts with a fairly plain admission: that we are not what we should be. Not that we are worthless — the opposite. We are made in God's image and deeply loved, which is exactly why our failures matter. The Christian claim is that Jesus dealt with those failures himself, at the cross, and that he rose again.
Becoming a Christian isn't passing a test or reaching a standard. It's closer to accepting a gift you couldn't have earned, and then spending the rest of your life discovering what it means.
If that raises more questions than it answers, good. Come and ask them. Nobody here will think less of you for doubting out loud.