"Shall I tell you the law of God in regard to the African race? If the white man who belongs to the chosen seed mixes his blood with the seed of Cain, the penalty, under the law of God, is death on the spot. This will always be so."An apologist might point out that interracial marriage was illegal in the United States until well into the 20th century. (on a similar note, I recently learned that it was common for religious people in the 1800's to believe the sun and the moon was inhabited, something I had previously thought was unique to early Mormonism)
While pointing out that a certain teaching may not have been unusual for its time does help illustrate that whoever put forth the teaching wasn't a monster but rather a product of his time, it does little to help demonstrate that person or the Church they represent is true or inspired. In fact, it does the exact opposite. By illustrating that an individual was a product of their time it does just that, shows that, like all of us, their beliefs and values came from their time and culture.
Which exactly what we don't want from Prophets, for them to be mere products of their time and culture.
The measure of a prophet is often how well they are able to predict future events. But how much value does that have? Having a heads up on a handful of world events doesn't seem like it would be significant enough reason for God to disrupt the normal order of things. Besides, that is not even the primary function a prophet plays. People look to prophets for spiritual guidance, instruction on how to live life and how to interact with the divine, so that should also be how they are measured: how well do their ethical teachings hold up against time.
If a prophet's teachings on how to live one's life are shown to have merely been an artifact of their cultural context, by definition it demonstrates that they were not inspired. Which makes it ironic that apologists use this reasoning so often.
But what if a Prophet were able to rise above the values of their time and place to teach ethics which the world may not value for decades or centuries to come? That would be an indicator of their prophetic value more so than an ability to predict future events.
After I left Mormonism I became a Baha'i for about a year or two. What attracted me most, (aside from the overwhelming spiritual experience I had when first encountering the writings of Bahá'u'lláh) were the advanced ethical teachings, Bahá'u'lláh, the faith's co-founder.
He lived in approximately the same era as Joseph Smith and Brigham Young, yet in a culture that was more oppressive and what we would see as backwards, the Middle East, specifically Persia (modern day Iran).
However from the beginning, Bahá'u'lláh placed emphasis on the values: religious tolerance, gender and racial equality (to the point of encouraging interracial marriage. Stark Contrast to the Brigham Young quote above) and many others with a similar flavor. These are values even the western world didn't come to appreciate for at least 100 years and in some ways continue struggling with.
Mormonism teaches that we should have low expectations of earlier prophets. Even after I left the Church I generally accepted the apologist explanation for various racist, sexist or simply unenlightened statements of earlier Church leaders. After all, these people were merely men who lived in a certain time and place and it felt unfair for me to expect them to reflect otherwise. However, having been a Baha'i raised that bar and I learned that I not only CAN but I SHOULD expect more from those who claim to be prophets in regard to moral teachings.
Having been a Baha'i taught me that I can expect Prophets to actually behave like a prophet. Prophets should be at the forefront of culture, raising their heads above their time and place to teach radical values that push and stretch people in ways that the secular world may not recognize until later decades or centuries, rather than being dragged kicking and screaming like most religions.
I sometimes say, if you want to know what things religious people will be teaching in 50-100 years, look at what liberal/progressives are teachings now. Liberal/Progressive teachings from the 50's or 60's which were seen as dangerous or radical the time are being taught over pulpits today. In a sense religions are inspired, not by God, but by the secular, progressive groups they often demonize, but delayed by a few decades.
Imagine if things were different. Imagine if instead of playing catch-up to cultural values, prophetic figures and religious leaders were the vanguard, challenging us to think in new, progressive ways. If this were the case, I might be able to believe religion is inspired. If their were a God, why is it that secular thinkers drive our moral direction?