Blasphemy is to teach a false message - an anti-Christ message. This is what mainstream Christianity teaches, a non-gospel of salvation by works - a blasphemous message from the start.
They teach that they accept a Jesus as their saviour, otherwise known as "mankind doing The Lord a favour." Can you believe this stuff? I hope so 'cos it's The Truth.
John 6:44 (KJV) No man can come to me, except the Father which hath sent me draw him: and I will raise him up at the last day.
John 6:65-66 (KJV) And he said, Therefore said I unto you, that no man can come unto me, except it were given unto him of my Father. 66 From that time many of his disciples went back, and walked no more with him.
They cannot accept what these Holy Scriptures teach i.e. that it's The Father who calls us, so they turn away to another gospel and to their religion just like the treacherous disciples above - blasphemy.