Peter Kirk takes Obama's conversion experience as evangelical (but see his comment below resisting the seemingly-uncontroversial inference from having an evangelical conversion experience to being an evangelical). The interview Peter links to in support actually leads me to conclude that he's definitely not an evangelical, and a case can even be made that there's nothing distinctively Christian in his personal faith. Let me first outline what I think the boundaries of evangelicalism can include, and then I'll look at some of the things Obama says that make me think he's outside the realm of evangelicalism and perhaps even not very specifically Christian. Much of the content here is adapted from comments in my conversation with Peter in the comments.
Theologically liberal views (at least compared to the status quo in evangelicalism) would include people who reject the substitutionary element of the atonement but retain a penal element (e.g. my co-blogger Wink), who support open theism but insist that God has a plan and will win in the end (e.g. philosophers Dean Zimmerman and Dale Tuggy), who are universalists of the sort that they're convinced everyone who goes to hell will eventually repent and follow Christ once they see the consequences of not doing so, and thus evangelism is still urgent, and hell is still real but just not eternally populated (e.g. Keith DeRose), who are inclusivists of the sort where Christ's sacrifice in fact atones for some in other religions because general revelation teaches them that God must provide a solution to the sin problem and trust him to do so (e.g. the C.S. Lewis view), that a homosexual lifestyle is morally ok but who feel the need to reinterpret scripture to defend such a view (e.g. I have a friend who holds such a view and is clearly an evangelical) rather than saying the Bible includes an immoral prohibition.
There are some who deny inerrancy (but really affirm it and just deny a straw man that they think inerrancy is), but I think actual denial of inerrancy is harder to maintain while being an evangelical. The Fuller Theological Seminary model makes an effort by still insisting that scripture is infallible on any moral teaching or theology within its pages. (Some at Fuller don't actually follow this. I know of one who thinks Paul was a complementarian but insists that we shouldn't be, and I think that moves out of the range of evangelicalism.) But I think you can say that there are errors in dates and place names in the Bible and still count as being within evangelicalism, just on the fringes. Once you start explicitly questioning the plain moral and theological teaching of scripture without trying to reinterpret it so that you at least believe scripture teaches your view, it's hard for me to see that as even on the fringes of evangelicalism. That's just theological liberalism in its most plain form.
So I'm certainly open to finding liberalizing tendencies within evangelicalism, even if one is on the fringes for holding certain views. Some of these are closer to the fringes than others (e.g. Wink's view of the atonement doesn't seem very extreme to me, just extreme-sounding to those unwilling to think very hard about what they've been taught). Those who combine several of these are more on the fringes than others. But one can be an evangelical and hold such views. It's a separate matter whether someone is a Christian but not an evangelical. I'm not saying here that one must be an evangelical to be a Christian. I know plenty of people whom I would not consider evangelicals but who do lay claim to being more broadly Christian. Very few Catholics are evangelicals, in my view, although I personally know a handful who I think are evangelical Catholics. I do think pious Catholics are Christian in a perfectly normal English usage of that term. I know a number of people who I think are Christians in mainline denominations who aren't evangelicals by the criteria I've outlined above. Some evangelicals want to restrict the term 'Christian' so that it only applies to evangelicals, but it's linguistically inappropriate to do that given what the term has come to mean.
But suppose someone denies the reality of hell and then expresses skepticism even about the existence of an afterlife in heaven. What if you say you pray, but then when you go on to explain what you do when praying it becomes clear that you're just maintaining an internal dialogue evaluating your life? What if you talk about a power that goes out of you when you speak the truth (rather than inflating your ego or playing rhetorical games), and then when your interviewer asks you if that's the Holy Spirit, you prefer to speak instead of just seeing a common recognition of truth outside of you? What if you're willing to talk of Jesus as your personal means of bridging the human-God gap but think of that in terms of reaching something higher rather than as the solution to a problem of sin? Speaking of sin, what if you admit to believing that there is such a thing but then define it entirely in terms of going against your own convictions, as if hypocrisy is the only sin? In the above-linked interview, Barack Obama did all these things.