Christians love to give their testimonies so I think it’s only appropriate that atheists do the same. The only difference is that for atheists it is the reverse–when they realized they no longer believed in God. Testimonies really don’t prove much, or at least they shouldn’t. Just because someone spent their youth on drugs and involved in criminal acts and then converted to Christianity has no bearing on whether God exists. Yet, Christians use testimonies like evidence and they are a good tool to convert people. There may be elements in a testimony that have some bearing on the investigation of reality–such as The Bible convinced me of this and so I believed or I read a Biblical critique and no longer believed, but overall testimonies are just someone’s life experience. They make for a good bio to listen to or read.
The testimonies valued by Christians are redemptive, the more sinful the better. It started to bother me as a Christian in my early twenties that I never did drugs, never had premarital sex and was never involved in a crime and yet the guy who did and then converted to Christianity got all the chicks while I was left on sidelines.
Women always like the bad boys. Thankfully, when I became an atheist it gave me a bit of the bad boy mystique because of the stigma associated with atheism and I stopped looking for the nonexistent “god-chosen” soulmate. Otherwise I would have had to buy a motorcycle to attract “the chicks.”