Twitter users quickly rounded on Williams, calling his tweet awful, offensive and unfunny.
Williams quickly apologised for the "cheap throwaway tweet" and called himself "a prat".
Williams issued another apology this morning, calling the tweet "a throwaway comment that I thought was funny ... sorry".
Fraser has performed for the church under her married name, Brooke Ligertwood, since her wedding to Scott Ligertwood in 2008. The pair have two children together.
Hillsong's website describes the couple as part of the "core leadership team" at Hillsong Los Angeles.
In New Zealand, Fraser is known for a string of classy pop hits, like Deciphering Me and Something in the Water, and she has won several New Zealand Music Awards.