How thoroughly modern of you.
Fewer than 100 years ago not a single Christian church would agree with your statement.
Is it likely that morality was misunderstood for 1900 years, or that society has traded morality for convenience?
100 years ago most Christian churches:
Supported white supremacy and considered "mixed marriages" immoral.
Opposed women's suffrage.
Taught that masturbation was a mortal sin.
100 years ago, if I'm not off on my chronology, the Catholic Church's official doctrine was that "freedom of religion" was a snare of Satan to be opposed by all loyal Catholics.
200 years ago (almost) all churches supported slavery as part of the normal human condition, supported in this, BTW, by fairly clear Biblical precedent.
Not too much further back than that many Christians believed the Christian thing to do was to burn heretics, or hang 'em, anyway.
We can go on, if you like.
So, yeah, morality can advance in Christian thought.
Which doesn't mean every innovation is automatically an improvement in morality. Sometimes it is indeed a trading of morality for convenience or popularity. Each case should be examined on its own merits, neither accepted or rejected for its history.
More likely that morality was misunderstood for 1900 years!