The wrong one would have been to sign the bill, relegating the world's most influential book to a status beside the state's nine official songs, two official state flowers and, just this year, its official state gun.
The easy one would be to let 10 days go by and allow the bill to become law without his signature.
The right and courageous one would be to veto the bill, forcing both houses of the legislature to override his veto with majority votes.
The legislature might do so - we hope it won't - but if it does it would be the first time since the post-Civil War Reconstruction period in which a Republican legislature in the state has overridden a veto by a Republican governor.
The House, which has a Republican super majority, passed the bill with only 55 votes last year, only five more than needed. The Senate, which also has a GOP super majority, passed it with only 19 votes this year, only two more than needed.
We don't believe the threat of voter outrage over the votes will do much to sway primary campaigns in August or re-election campaigns in November, but we hope enough House or Senate members will re-think their position on the bill to prevent the override.
We have said, as Haslam did when he vetoed the bill, that making the Bible the state book trivializes it as less than it is - the inspired word of God, a history of God's people and a manual that contains everything needed for a commitment to personal salvation - and that it, arguably, violates both the United States Constitution and Tennessee Constitution. Tennessee Attorney General Herbert Slatery thinks it does, anyway.
Tennessee should be proud of, among other things, being the first state to launch an animal abuse registry, the first to launch an Agricultural Hall of Fame and the first to bottle Coca-Cola. It should not add "the first to make the Bible its official book" to that list.