Living in Texas, Christianity here is highly influenced by revivalism and its decision-theology. Even traditions and denominations that reject this belief and practice can't help but be influenced by it, even if only to interact with other Christians around them. Yesterday some life-long Christians were asking about conversion experiences and the anxiety they sometimes had because they had never experienced a dramatic conversion but had been raised and nurtured in the faith their entire lives. They sometimes questioned their faith because they could not point to a date on the calendar as the day they 'came to Christ.'
I understand conversion experiences. Even dramatic ones. We probably all know people who were converted this way. That said, making such a mark-the-calendar-when-you-became-a-Christian experience a 'requirement' (yes, I've heard it said like this) by which we validate someone's faith is rubbish. Not only is it nonsense, it puts our faith in the wrong place.
Finding assurance of your salvation because you 'made a decision for Christ' on such-and-such date is placing your faith (trust) IN your faith (experience) instead of placing your faith (trust) in the life and work of Christ Jesus for sinners. Our faith will always be imperfect. In times of doubt and trial, our faith might waiver and falter. If you find assurance in your own faith, you will be tormented by these realities. Instead, cling to Christ and his perfect, steadfast love and grace. Don't look back on some decision you made to find whether or not you are a Christian...look way back to the cross and Jesus' work as the lamb who took away the sins of the world.