The word 'Christian' means many things to many people.....Satan believes that Jesus is God and He tested Him. Satan believes that Jesus was born to bear all the sins for all mankind.....By this 'belief', indeed Satan can also be 'qualified' to be a 'Christian', but the Bible is very clear that He will be thrown into the lake of fire (hell) and suffer the judgment of God forever and forever.
No one can be saved just to simply proclaim: "I am a Christian!" There is no such teaching in the Bible. In fact, the word Christian is used just one or two times in the Bible. We can only be saved when we are born-again in His Spirit. A rose still smell good even it is called by another name...and the reverse is also true. Only by believing and trusting the redeeming blood of Jesus can we then be saved from the wrath of God and to gain our rightful place in His kingdom.....God says: Repent and be saved! He didn't tell us: Be Christian and be saved! We must repent...repent our wayward life, sincerely obey His commandments, sincerely not to repeat our sins.....Salvation is achieve through "REPENTENCE" and this can only done with the indwelling of the Holy Spirit, and by only putting all our trust in our Saviour, Christ Jesus, in His shed blood on the Cross, in His crucifixion and in His resurrection from the grave.
So, you now understand!!!! Yes....Hilter may be a 'Christian'.....or may not be.....let God decide.....and he may labelled himself with the title, I could mean nothing to God if He didn't repent....and did he repent....only God knows.