Christianity is often used as an excuse for bad behavior. Look at how Nancy Pelosi calls upon her Catholic “faith” to justify forcing churches to provide contraception, when Catholic doctrine specifically teaches the exact opposite. The popular belief is to call oneself a Christian and then define it as whatever pleases you or pushes your agenda in order to justify your actions.
Hitler called himself a Christian, despite Nazi philosophy being deeply rooted in the occult (Google swastika).
“I say: My feelings as a Christian points me to my Lord and Savior as a fighter. It points me to the man who once in loneliness, surrounded only by a few followers, recognized these Jews for what they were and summoned men to fight against them and who, God’s truth! was greatest not as a sufferer but as a fighter. .. How terrific was His fight for the world against the Jewish poison.” -Hitler
Hitler’s words are rebutted by Romans 1:16, “For I am not ashamed of the Gospel of Christ for it is the power of God to salvation for everyone who believes, first to the Jew then to the Gentile.” However, this and other such statements lead some (especially those looking to do damage to Believers) to preach that Hitler was a Christian. However, one cannot be a Christian simply by calling yourself a Christian, quoting the Bible, or talking about God. Even Satan quoted the Bible (Matt 4), so by that logic are we to believe that he is a Christian too?
A Christian is defined as someone who follows Christ, meaning someone who has admitted that they are a sinner (Romans 3:23), believes Jesus died to pay for their penalty caused by sin (Romans 6:23), and has confessed and asked him to forgive you (Romans 10:9-10). The result of this is salvation and a deep desire behave as Christ did while on earth. Any other additional doctrine is antithetical to the Bible and not defined as true Christianity.