No. A person is only a Christian if they are devoted to Christ. Being born into a Christian family doesn't make one a Christian. Being a Christian is a personal decision and a personal commitment based on choosing to be in a love relationship with God and follow Christ with one's whole life. So saying, the person of your question is an atheist, not a Christian, and he or she is just as much a non-Christian as a Muslim, Buddhist, or Hindu.

Do you consider someone a Christian if they were raised in a Christian family and became, and still are, an atheist?

Would you consider them as Non-Christian as a Muslim or a Buddhist or a Hindu?