That if you confess with your mouth, “Jesus is Lord,” and believe in your heart that God raised him from the dead, you will be saved. Romans 10:9
I know that Britney attended a Southern Baptist church when she was a girl and had a Christian upbringing, but I don’t know what sort of profession of faith she had (like the one outlined in Romans 10:9). We cannot know anyone’s salvation, really.
Someone may say they are a Christian and even use Scripture to back it up. That doesn’t mean they are a Christian. Many define the word Christian differently. Words could be deceiving.
A life of good works may be an indication of salvation, then again non-believers do good things for other people all the time. Then again, a Christian life should reveal some sort of fruitfulness--their attitude, acts of kindness, generosity should be evident.
I believe someone could say they aren’t a Christian and actually be a Christian. They are basing their relationship with God on their feelings, not the promises of God. Feelings deceive us.
Sometimes I can tell if someone is a Christian. Maybe it’s the Holy Spirit inside me and them that is communicating this information.
Just because someone is not living a Christian life, doesn’t mean they aren’t a Christian. Christians sin ALL THE TIME! Many go through periods of depression, rebellion and anger. In the Bible, Abraham lied, Moses killed a man and David slept with another man’s wife. Does that mean they didn’t have a relationship with God? No, it just meant their life took a little detour, they got lost, then eventually found their way back.
So we cannot say someone like Britney Spears “was” a Christian. You are either a Christian or you are not a Christian. Only God knows for sure.
We should pray for everyone’s salvation and not judge anyone too quickly.