From John Wesley’s sermon “On the Wedding Garment“:
When things of an indifferent nature are represented as necessary to salvation, it is a folly of the same kind, though not of the same magnitude. Indeed, it is not a little sin to represent trifles as necessary to salvation; such as going of pilgrimages, or anything that is not expressly enjoined in the Holy Scripture. Among these we may undoubtedly rank orthodoxy, or right opinions. We know, indeed, that wrong opinions in religion naturally lead to wrong tempers, or wrong practices; and that, consequently, it is our bounden duty to pray that we may have a right judgment in all things. But still a man may judge as accurately as the devil, and yet be as wicked as he.
Right opinions about every doctrine are no guarantee of holiness. Does Wesley say that orthodoxy is a trifle?
The real danger of bad doctrine is bad practice.
John Meunier 
Orthopraxy > Orthodoxy. Always. Sorry, Chesterton. It’s the sheep and the goats. Neither really knew the rules before they were sorted, but the ones who DID what was right were rewarded.
Colin, you’re pushing Matthew 25 too far. If you push it too far you can make a case from Matthew 25 for justification by works.
Wesley understood that orthodoxy and orthopraxy at their best, are intimately integrated. Of course, we human beings, who often force ourselves into construing things into and either/or dichotomy, are so engineered in modernity into binary thinking we find it difficult to understand how two things, which we have deemed to be opposites, actually work together.
I find this issue of practice and doctrine (note, I did not say versus) to be quite a vital question.
Wesley’s concern seemed to be primarily that doctrine was not enough. It was not sufficient for true religion. It may not have even been necessary – as he wrote more than once that he’d rather have love with wrong opinions and right opinions without love.
But – as in this quote – he also sees how bad doctrines can lead to bad practice of the faith. This is why he spent so much energy arguing against predestination and found the Moravians so vexing.
The key is that right practice (outward actions) and right opinions (correct doctrine) neither one were a sign of true faith. It was a right heart that mattered.
Orthokardia > than orthopraxy or orthodoxy.
Actually it is not a case of either/or but both/and.
The Bible talks about “sound doctrine.” It is not an option. It does matter what you believe.
The Bible also has an often repeated chorus of “obedience.” Ignore it at your peril.
As for the right heart, didn’t Jesus say something about knowing those who love him by keeping his commandments?