Speaking as an individual here, not on behalf of NA...

As an openly Atheist member of Narcotics Anonymous, with 23 years clean time, I'm here to say Christianity as a barrier to recovery is a matter of personal choice. Yes, I'm an Atheist with a higher power, it's my [G]roup [O]f [D]rug addicts. I kibitz with them about how to stop using, losing the desire to use and finding a new way to live. The Third Tradition of any 12-Step Fellowship clearly says there is only one requirement for membership. In the case of NA, that requirement is a desire to stop using. AA states a desire to stop drinking. They literally cannot kick you out for choosing a secular life. In my experience, anything beyond a brief mention of someone's faith or Atheism is frowned upon, because every addict's choice of a higher power or lack thereof is their own to make.

The principles of the 12-Steps, though adapted from Christian (or Muslim, Hindu, Jewish or you name it, even select Atheist) teachings, they really don't have anything to do with religion at all. They have a lot to do with being human. They are guides that teach people about being honest (particularly with themselves and about their addiction), having an open mind, willingness to change, willingness to amend the wrongs they have committed in the past, being accountable going forward, and participating in selfless service to others inside and outside NA. This is not about virtue; it's about how, for addicts, the opposite of these is a recipe for active addiction.

The thing about addiction is, the ego is a strong force that perpetuates cycles of arrogance and self-righteousness (among potentially many other issues). Using religion as a barrier to recovery is nothing more than an excuse to resume using. And it is certainly not the only addict-contrived excuse to get loaded. There's too many to count; and I have known dozens of people who are now dead as a result of that type of excuse and the using that followed.

The turning point for any addict is coming to terms with the trauma that created the pain they are trying to cover up. That's why honesty is so important; once that pain is out in the open, it can be dealt with and healing can occur. But that's not a simple problem to solve. The route to such clarity varies widely from one addict to another. The 12 Steps create an environment to facilitate revealing such core issues but certain issues may escape detection. Some people will require therapeutic or legal intervention (we call it "Outside Help for Outside Issues") to get "there". Some never get there and white-knuckle it to stay clean. Or kill themselves with something other than drugs.

12-Step programs like NA are NOT highly successful. I think it's about 1 in 10 that make it. Probably even less. Our stats are probably skewed by attendance coerced by the justice system; who knows, there is no science to collecting surveillance in an anonymous program. We even make efforts to let the justice system know that we are not taking attendance or verifying identities of attendees; our 12 Traditions make us resistant to such observation. This isn't the program for people who require those kinds of stats.

What I can say, when I look at the people I got clean with, the people who we hung tight together with and were committed to staying clean no matter what, nearly all of them are still clean. Many of them without relapse (including myself). And so are the serious members who were here when I arrived. Those who told me it was OK if I didn't believe in God, that I just had to be open to the idea that maybe my decision-making skills were prone to creating problems rather than solutions.

NA makes no claims of any performance. It's just a thing some people found that works for those who work it. Those being the members who don't use in-between or at meetings, come on a regular basis, work steps and serve others. Anyone else isn't actually working this program, they're doing something else. We don't insist we're the only way to recovery. We humbly accept this program comes with no guarantees. If other methods work for others, awesome! Go to what works for you, and hopefully that doesn't include a dependency on doctor-prescribed dope.