Rather than divert the "Fractured Protestantism" thread, I will ask here:
What makes someone a Baptist? Being a member or attending a Baptist Church? What if you move and then become involved in a church of a different colour, eg Anglican? Would you then cease to be a Baptist?
Simple, you need to agree with the forum's Statement of Faith. But many 'non-denominational' churches would also agree with this - does that make then effectively Baptist? Or perhaps you must have the word 'baptist' in your church name? But some Baptist churches don't. Or perhaps 'non-denominational' is very different in America than the UK. JM says that they are definitely NOT Baptist. Why not?
As a UK Baptist, I find that the Statement of Faith here is lacking an important distinctive of Baptists - congregational government. The local congregation agrees and appoints leaders, discusses and takes decisions, which is one reason why membership is important. And in the UK this is what would stop other groupings from being 'Baptist'.