Concerning your question on credit used for underwriting, yes in many states the majority of insurers do use credit as a tool in their decision to accept or decline a risk. This is a result of historical data that supports the fact that persons with adverse or poor credit tend to have more frequent, and more severe claims....which increases everyone's rates. Also, a person with financial problems may not take the same care to do routine maintenence etc. on their home, again resulting in higher claims costs. I understand your frustration, but you were not singled out. There should be a "pool" in your state that will insure you.
I am curious about the reason your coverage cancelled, the "agent paid the company late" ? Don't you have a receipt? If so, what is the date on it, vs the cancellation date? Are they obligated to accept it based on the procedures they have in place for reinstatements? If so, they may have to reinstate simply because it is a procedure - they ususally can not single out one insured to apply a new rule to. However, if they are forced to reinstate you will possibly be Non Renewed for credit at the end of the policy term. How long had you had this insurance? If some history was established, with good claims experience, perhaps an appeal directly to the underwriter at the company would help. Did your credit deteriorate after they originally accepted you? If not, then ask them what has changed in the risk, if your credit is unchanged or even improved some then again you may be able to work it out. Otherwise, as the prior post stressed, you need to secure coverage immediately. Good luck.