I have a friend who is no longer religious and he asked me for a loan am i able to lend with ribis if he is not keeping kosher or Shabbos?
This should not be done.
It might be permitted to lend a mumar money with interest. However, applying the concept of a mumar to modern-day secular people is difficult, even for somebody who was once observant and is no longer keeper kosher and Shabbos.
The Beis Yosef and Shulchan Aruch (159:2) write that somebody who chooses forbidden foods over kosher foods, even when both are otherwise the same, is a mumar le-hachis and it is permitted to lend him money with interest. However, the Bach argues that it is only permitted to lend a true mumar (somebody who “leaves the faith”) on interest, and the Rema adds that some are stringent even concerning a mumar.
In addition, by lending him with interest you will be offending him, and distancing him still further from religion.