Christianity

What exactly constitutes a Christian?

Is it someone who attends church all the time and constantly preaches the Word of the Lord, yet has so much hatred in their hearts, they do not know how to forgive and forget when the Bible stresses forgiveness? Or is it someone who believes in God and follows His word, yet doesn't feel the need to preach to others, but that person is a forgiving person who doesn't hold grudges and can move forward? Which one are you? Which one is the correct version of a Christian?

As usual, this blog stems from a real situation in my life. My brother's stupid baby mama is one of the most evil and vindictive persons I have ever met, yet she claims she is a Christian. I beg to differ.

This girl is so evil and vindictive, I have never seen anyone like her. She is the devil in disguise. How can anyone be so cold as to not allow the father of their child or anyone else in that family to talk to or visit the child? My brother loves his first child to death and it kills him that he cannot be an active part of her life. Because he chose not to be with the mother, she has taken things to new levels where she doesn't answer any of his calls or mine, hangs up in our faces and has resorted to telling my brother he will never see his daughter again. When confronted about the situation and we tell her that it's been 7 years and she needs to get over my brother, she denies that she still wants him, but her actions speak differently. It's really sad and the past few days were really difficult for me as I was in San Antonio where she lives and I called the mother's house to try and talk to or see my niece, but was denied that opportunity. The mother has tried to hide by changing her phone numbers several times, but little does she know that with technology these days, anyone can be found and we did just that...found her. I called and as soon as she recognized my voice, she hung up. She didn't even bother to find out what I wanted, nor did she care. She coldly hung up in my face then didn't answer any of my calls after that. I was furious and almost drove to her house to let her see I found out where she lives although she thinks no one knows, but I decided to pray instead.

With that being said, I ask again...what exactly constitutes calling yourself a Christian? Can someone please tell me so I am no longer confused?