Followers of Jesus Christ are called Christians.  Claiming to be a Christian when you are not is taking the Lord’s name in vain.  This is being a hypocrite and all hypocrites will go into the lake of fire with the unprofitable servants.

Exodus 20:7, “Thou shalt not take the name of the Lord thy God in vain; for the Lord will not hold him guiltless that taketh his name in vain.”

Matthew 24:50-51

50 “The lord of that servant shall come in a day when he looketh not for him, and in an hour that he is not aware of,”

51 “And shall cut him asunder, and appoint him his portion with the hypocrites: there shall be weeping and gnashing of teeth.”

Swearing in the name of the Lord is also taking His name in vain.