The word
ātmā
has been used in multiple ways in the Vedic literature for God, for the soul, for the mind, and for the intellect.  This verse typifies all these uses.  Shree Krishna describes the
karm yogi
who is
yog yukt
(united in consciousness with God).  He says that such a noble soul is  1)
viśhuddhātmā
, of purified intellect, 2)
vijitātmā
, who has conquered the mind, and 3)
jitendriya
, one who has controlled the senses.
Such
karm yogis
, with purified intellect, see God situated in all living beings, and behave respectfully toward everyone without attachment.  Since their actions are not motivated by the desire for self-enjoyment, their knowledge is progressively clarified.  As their desires are eliminated, the senses, mind, and intellect that were being propelled for sense pleasures come under control.  These instruments are now available for the service of the Lord.  Devotional service leads to realized knowledge from within.  In this way,
karm-yog
naturally brings about these successive stages of enlightenment, and hence is no different from
karm sanyās
.