I see these prepositional phrases as follows:
DIKAIOSUNH is the subject dealt with here, not PISTIS. This
righteousness is revealed EN AUTWi ( the gospel, as opposed to the OT
Law). The righteousness revealed by God is out of faith (EK
PISTEWS - an ablative of source) as opposed to another source
like works of the Law. And not only is its beginning by faith, but
also its goal or end (EIS PISTIN) is faith. A continuum and increase
of faith is required because "hO DE DIDAIOS EK PISTEWS ZHSETAI." The
"rightous man" who has appropriated the rightousness that begins and
ends with fatih, will live by faith ( EK PISTEWS - ablative of
means). These prepositional phrases can be seen in other ways and I
am open to other possiblities, but the context of faith in the gospel
as the power of God to transform the sinner into the righteous man
is consistent with this interpretation.
Blessings!!
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Fred Haltom
Associate Professor Christian Ministry
Central Bible College
haltom@cbcag.edu