Protestants often raise Tobit 12:9 to argue against the authenticity of the Deuterocanon. The argument goes something like this. Tobit 12:9 says that, “For almsgiving delivers from death, and it will purge away every sin. Those who perform deeds of charity and of righteousness will have fullness of life.” This, they argue, is works-righteousness. This contradicts the parts of the Bible they know to be true, and therefore, is not itself a part of the Bible. Under this theory, Tobit isn’t even an uninspired-but-useful-for-edification book: it’s a book promoting a gospel contrary to that of Christ.
There are plenty of problems with this theory. For starters, you can’t start with a theory like sola fide, and determine which books of the Bible are in or out based upon that. That was Luther’s criterion for determining whether or not to include books like Tobit, but also books like the Epistle of James, which virtually all Christians today accept. If you do that, your theory of justification isn’t based on the Bible: your Bible is based on your theory of justification. So a true subservience to Scripture as God’s word would require an open-mindedness on this point. If this is Scripture, then perhaps interpretations which contradict it, like sola fide, need to be changed. After all, sola fide isn’t God-breathed. Holy Scripture is.
But second, is Tobit really saying you can buy your way to Heaven, or work your way to Heaven? Of course not. The message here is little different than that of Proverbs 19:17, “One who is gracious to a poor man lends to the LORD, And He will repay him for his good deed.” Or better yet, Jesus’ statement in Matthew 19:21-22. A rich man comes to him and asks how to get to Heaven. Jesus asks him if he’s following the Law; he is. Then Jesus says: “If you want to be perfect, go, sell your possessions and give to the poor, and you will have treasure in heaven. Then come, follow me.” When the young man heard this, he went away sad, because he had great wealth. See also the parallel account in Mark 10:17-23. Taken in isolation, the way that certain Protestants do with Tobit 12:9, Jesus is saying, “you can earn your way to Heaven, just pay 100% of your worldly goods.” In fact, even before he gets to the “come follow Me” stage, the man who gives away this 100% already will a treasure in Heaven (since that treasure precedes the following of Christ given His particular syntax). But of course Jesus isn’t saying, “you don’t have to follow Me, you just have to give lots of money away.” He’s saying that giving everything you have to the poor because of Him is a form of faithful obedience, the sort of Faith/Works combo that saves you.
No one who hears that would give everything they had unless they believed; and not just a little (like the man in the passage), but a lot. Believed so much that they were willing to give everything up for Jesus’ name. That’s a work, yes, but it’s also an act of faith.
So the message in Tobit is identical to the message of Christ on this point. If anything, it shows that Tobit is harmonious with the Gospel message. If it’s a reason to do anything, it’s a reason to trust the Deuterocanon.