Yes. If you are located in the United States, you may legally marry any couple who requests this service from you as long as it is in line with local laws, regardless of their religion. If you are outside of the United States, you may perform a wedding ritual for purely ceremonial purposes, but you must research local laws to find out what steps you may need to take to be able to legally officiate weddings in your country.
As a minister, the ceremonies you agree to perform is entirely up to your discretion. You should never perform a ceremony that makes you uncomfortable in any way. You should never perform a ceremony that would require you to violate The Satanic Temple’s Code of Conduct. Please remember that as a Minister of Satan you will be viewed as a model of the seven tenets and a representative of The Satanic Temple in every ceremony you perform. Beyond that: do as you will.
Remember that you are required to submit a description of any ceremony you perform using the Ritual Notification form. Please go to your Minister’s Dashboard for rules about when the form needs to be submitted and what information you must provide.