Here's my take on it - based on the novels, not any real life opinions I have.
In the DV, followers of evil get "power now" types of rewards. Evil is the great shortcut when it comes the bad things helping you. Want to death curse someone and you don't have time to learn magic? Then you do a rite that helps The Walker Behind and someone dies. Want real power - including being able to live until something kills you? Then take up that coin and share your body with a Fallen Angel. Tired of watching the bad guys skate on those charges just because they have good lawyers? Then become Hexenwolves with a demonic co-pilot and kill those bastards.
In short, it's "Go evil and get your reward now, not later" because the forces of evil are actively recruiting the morally weak.
On the other hand, the forces of good are all "do good now and when you die we'll reward you". You don't see angels going around "tempting" people to be good. You don't get bribes for or make deals with the forces of good. If you're not good for the sake of good then they hope you see the light - but they don't offer "coins of goodness" to the nickel heads and get into a bidding war with hell over someone's soul.
The swords? They aren't bribes. You have to be the right person before you get offered one. They are tools that a few people get offer, not rewards or bribes, and they come with a strong obligation - you commit to putting heaven's work ahead of your life and family.
We could get into a debate over whether part X of a religion is good or evil (as seen by outsiders) but the books make that irrelevant. The existence of an agnostic knight shows that the forces of good are concerned with motives and actions - not dogma.
So when it comes to followers of evil, I'd give them other powers (including creature features and sponsored magic) and maybe minions rather than adopting the True Faith stuff.
Richard
To some degree I agree with your line of thinking. It reminds me of Yoda telling Luke that the dark side was quicker, easier, more seductive, but not more powerful.
It's always harder and longer to follow the path of light than the short jog into darkness. We see this demonstrated in human nature over and over again. Good can lead to slow gradual payoffs with a lot of sacrifice along the way, where evil tends to pay off right now, but often ultimately leads to terrible sacrifice later.
That being said, Jim seems to take an approach similar to many settings I've seen (such as the World of Darkness), where the power of belief is far more a factor than the nature and contributions of what is being believed in. For instance in Mage, strong belief could manifest changes in reality, and the stronger the belief, the greater the changes, hence magic and the power of faith. A mage might believe in his own power to create change where the faithful believes in a higher power to create change, but ultimately the strength of the belief was where the real mojo came from. One could see it as an act of faith as opposed to an act of will, but both needing sufficient conviction to effect any change.
In my own spin on it for purposes of this fiction, it could be said that belief is the conduit by which greater powers invest themselves, a kind of symbiosis where the supernatural needs belief to have power, and rewards that belief with power towards ends that are consistent with its goals and nature. But for wizards, that power comes from their lineage and the ability to channel power through their own convictions to effect change (much like the Mage mythos).
Point being, yes, believe in a power enough (either good or evil) and they will respond. Believe in your own power enough and you can do it yourself, for good or for ill, hence the distinction between white and black magic.