The Bishop is the quickest way to get checkmate. As you can see all of whites pieces are pretty locked on d7. Can move Qg4 and threaten mate that is almost unstoppable. I'll show you a line where it isn't Qg4 that wins.
2. Nxc5 Bh3+ 3. Kc2 f5 4. Rd4 Qf2 5. e6 and I'm not sure what you think black should do, but it is very bad.