As it is, it is no longer I myself who do it, but it is sin living in me.
OJBBut now it is no longer I doing this, but [the power of] Chet (Sin) which dwells within me.
TCENTBut now it is no longer I who do it, but sin that dwells in me.
T4TSo, it is not that I do evil things because I wish to do them. Instead, what happens is that I do sinful things because the desire to sin causes me to do them. The desire to sin ◄is within/permeates► me [PRS].