If you are a believer, this argument might appeal to you:
(1) It's absolutely wrong to blaspheme against God, as in swearing at God. Even if a thousand/million/bajillion people were going to die if you didn't.
(2) So there are some moral absolutes.
If you don't think this works then think of some worse offense against God, maybe killing him, like they did to Our Lord. Then stipulate once more that a thousand/million/bajillion people will die if you don't.
When the divine comes in this seems to some extent to release us from the intuitive pull which consequentialist 'what if a bajillion people'-type objections have.
If you think the first example works, then acting contrary to other moral absolutes can be viewed as violations of God's law, and thus equally worse or bad offenses against God; after all, if saying certain words to God is absolutely wrong, then surely violating his commands about even more important things, like killing innocent humans, is also absolutely wrong.