The tactic I'm currently using is to advance deism as a more rational alternative to dogmatic theology.
I don't have a desire to convert people from belief to non-belief per se. If a person has a deeply-held belief in feng shui, the result is that they spend time and money re-arranging their furniture. Their irrational belief doesn't have a negative effect on my life, or (as far as I can see) on society as a whole, beyond the endorsement of irrational thinking itself.
My battle with religion is more focused on mitigating the harmful effects than eliminating the beliefs themselves. As an American in 2007, I'd like to foster a climate in which abortion is available, stem cell research can be federally funded, and intelligent design can only earn its way into the classroom when (yeah, right) it furnishes enough evidence to be accepted by the scientific community. My quarrel is thus more with fundamentalists and evangelicals than with religious people as a whole.
I'm willing to settle for moving someone from harmful belief to less harmful belief. Someone may have an "inner experience" of God, but it's their choice to map that experience onto a set of dogma. People in a Christian culture tend to adopt Christian dogma, those in a Muslim culture tend to adopt Muslim dogma, those in a Hindu culture tend to adopt Hindu dogma, etc. To echo an earlier poster in this thread, my experience of fear while walking alone in the woods doesn't confirm that I'm being stalked by Bigfoot. It's my choice to interpret the inner experience that way.
If someone has an inner experience of God, and they attribute the experience to a natural sense of awe and wonder for the creator of the universe, it doesn't necessarily follow that "heaven and hell are real, and only the blood of Jesus can purchase entry into heaven." Yes, you've had an experience of God. Now, go and discover the universe, the real universe, that you believe he created. Yes, that universe is awesome and incredible, and (as the signature of the creator you experienced) is worthy of study and devotion. The actual realized universe which you yourself were born into, not the dust-covered words of someone who was born into a different time and place. Learn about it, see how God really works.
I don't know if this will be effective in moving a hard-core fundamentalist toward rationality. It's a tactic which may be effective in some circumstances, and will undoubtedly be completely ineffective in others. I do think that moving someone from belief to unbelief may be more of a leap than many people can make. Maybe in some of those cases, moving them from an anti-science belief to a science-neutral or even a pro-science belief will still be a realistic goal.