Gospel presentations for medieval Seventh-day Adventists

God’s prophet to the Seventh-day Adventists once dreamed of how medieval the members of her own church were, when she lived in Battle Creek (Ellen G. White, Testimonies for the Church, Vol. 1, page 578).

See http://www.everythingimportant.org/seventhdayAdventists/dupery.htm

How should the everlasting gospel be presented to medieval Seventh-day Adventists like this?