You can replace 1 cup of molasses with the same amount of honey, dark corn syrup, or maple syrup, but you'll forgo the big,
robust flavor of molasses.
For baked goods, you can replace 1 cup of molasses with a mixture of 3/4 cup sugar, 1 1/4 teaspoons cream of tartar, and 1/4 cup of hot water or other liquid that is in the recipe. If there are spices in the recipe, increase them just a little to compensate for the loss of the molasses flavor.
One caution: But don't use blackstrap molasses if your recipe calls for light molasses: blackstrap has an even more intense flavor that may be overpowering.