What you’re calling “value drift,” Evangelical Christians call “backsliding.” The idea is you’ve taken steps toward a countercultural lifestyle in line with your values, but now you’re sliding back toward the mainstream—for an Evangelical Christian, an example would be binge drinking with friends. Backsliding is common and Evangelicals use many of the techniques listed above to counteract it.
Evangelicals heavily emphasize community. Christians are encouraged to attend services, join a small group Bible study, socialize with each other, and marry other Christians.
I also remember being encouraged to establish good habits and stick with them—for example, reading the Bible every morning.
We also, of course, begin with a public commitment to Christianity. And community members will pull you aside and have a chat with you (read: judge you) if they think you’re in danger of backsliding.
I’ve seen all of these strategies work, although some have undesirable side effects.