My MacBook is unable to connect to a wireless network due to airport card issue. While I figure out how to fix/replace the card, is there a way to share my iPhone's connection to a wireless network with my MacBook (e.g. via Bluetooth)?
That all depends. If by "wireless network" you are referring to an EDGE (2G) or 3G/4G connection then it would be as simple as going in to your iPhone's settings and turning tethering on. However, in the much more likely scenario that you are referring to a Wi-Fi network then the answer is a simple "No" unless you are not afraid of jailbreaking your device. In case you are unaware, jailbreaking an iPhone is a very simple and completely legal operation that removes many of Apple's restrictions and allows the iPhone to run third-party apps. If you have jailbroken your iPhone then there are a number of apps that could do what you are looking for. I recommend MyWi, though I believe that PDANet would work as well.
Well what I understand from your Question is you want to share iPhone connection to your Macbook. You can do it. Follow this:
1)Just go to Settings--> Personal Hotspot(Below WiFi)
2) Turn on Personal Hotspot where you will have two option for sharing your internet: Via USB and Via WiFi.
Since your Wifi has problem select Via USB and plug in your iPhone to Macbook and start surfing.