As a matter of fact, I do advocate against the killing of babies. But, I see no reason why abortion is your litmus test for Christianity.
In the twelfth century, after all, Christians celebrated successful abortions as a life-saving miracle. In the 19th and 20th centuries, Christians were indifferent on the issue. It wasn’t till a conservative evangelical movement rising alongside Nixon’s Southern Strategy did the majority of Christians start protesting the procedure.
So, let me ask this: if Christians didn’t actively advocate against abortion until the mid 20th century, does that mean Christianity never existed by your definition until then?