The list of possible or spurious Bach works extends beyond the BWV-catalogue. Reinmar Emans made a list (around 1997) of chorale preludes that could possibly have been written by Johann Sebastian Bach. The list contains 198 items. Since 1997 some of the works on the list have been positively attributed to other composers, some are supposed to have been written by other composers, and some are still a possible candidate for Bach’s authorship. The prelude to "Herr Jesu Christ, wahr' Mensch und Gott" (Emans 100) is one of them. It is a powerful fugue on the first phrase of the choral melody. That's a difficult melody (harmonically) to build a fugue on, so Bach or not, whoever wrote it, shows his harmonic ability very well. The voice leading on the other hand is in places not very expertly done. The question remains: Bach or not Bach?
The recording was done with the Hauptwerk software and the sampleset, made by Voxus, of the Müller organ in the Sint Bavokerk, Haarlem (http://www.voxusorgans.com/en/product/haarlem).
Score available here: http://partitura.org/index.php/johann-sebastian-bach-herr-jesu-christ-waht-mensch-und-gott-emans-100