There are a tonne of definitions of a Christian - depends on the denomination..
Gotta agree with the Doc on this one. Defining yourself as a "christian" or not, kinda depends on how you interpret the Bible. Look at the differences between 2 groups who use the same book........Northern and Southern Baptist.
And..........the Christians (as they currently believe), are WRONG.
Yeshua didn't come to replace the law (Torah), He came to expand upon it and bring it to the people who WEREN'T Jewish. He also renewed the covenant between God and the descendants of Abraham (remember......Yeshua was Jewish).
Now......when Rome sacked Jerusalem after they killed Yeshua, they took the teachings He'd laid down, and modified them to suit their own needs (i.e. control of the various pagan nations Rome had), which is why Easter is on the Spring Solstice (complete with Sunrise Service), when in reality, Easter should ALWAYS come after Passover, which is why Yeshua was in Jerusalem in the first place.
They also did it with the Winter Solstice, which is what the Catholics determined (as per the pagan customs of Rome), was the birth of Yeshua, when in reality it was more like October.
Now.......with that kind of start off, as well as with the heavy editing of the Bible by the Niecine council (because they were deciding what the common people would be allowed access to), is it any wonder why your friend said what they said? They hope they're wrong because they can SEE that they're wrong!
And......they want to save others from making the same fatal mistake!