How to make the bandpass filter stable?

Hello,

I am designing a multiple feedback bandpass filter but i get a bode plot which shows its unstable. I have attached the bode plot below, Could anyone share your opinion how to make it stable or my analysis is wrong?

Code:

Reference for designing BandPass Filter: http://www.ecircuitcenter.com/Circuits/MFB_bandpass/MFB_bandpass.htm

Thank you.