There’s no question that Mormonism was racist. Here’s the argument:
1. The LDS Church denied the priesthood to blacks.
2. The priesthood is positively valuable (from the Mormon perspective).
3. [from 1&2] The LDS Church denied something of value to a group of people based on their skin color.
4. To deny something of value to a group of people based on their skin color is racist.
5. [from 3&4] Mormonism was racist.
Of course, Mormonism no longer denies the priesthood to blacks. The LDS Church changed this policy in 1978. But does this change its status as racist? I don’t think so. The change in policy came from a divine “revelation” to Spencer W. Kimball. This implies that it was God’s decision to rescind the ban. This latter claim, in turn, implies that it was God’s decision to institute the ban. Why? Because if it wasn’t God’s decision to institute the ban, then the leadership of the church could have changed the policy without a revelation. It takes God to undo what God has done.
By lifting the ban with a revelation rather than an apology, the LDS Church still gives divine sanction to the previous ban. But this implies that the Mormon God is racist. Therefore, Mormonism is still racist. Only an apology can erase this fact.