Ideal Op Amp in Closed Loop
Yes, if the other components are ideal too and there is no parasitic capacitance, series inductance, etc.  With these effects, every resistor has a non-flat frequency response.  Since your feedback path will contain resistors, the frequency response will likewise be non-flat.

Then there are other considerations depending on how obsessive you want to get.  Regardless of how ideal the opamp may be, there will be some finite propagation time of the feedback signal back to a opamp input.  This represents a different phase shift at different frequencies, which will again make the frequency response non-flat and can make the whole system unstable.