Requirements for Ordination

What specifically are the requirements for a minister to be ordained? In short, the requirements vary from state to state and from denomination to denomination. Some churches do not have an ordination process to be titled a minister, while for other churches and religious practices the ordination method can be quite specific and involved. In these churches, the powers that be might wish to promote a view of ordination as holy or sacred, going so far as to say the ordained person has been selected by God.
From a legal perspective, however, this does not matter. A requirement by government officials to demand a religious test runs counter to the U.S. Constitution. What is needed for a personal to be considered legally ordained is for a church that is recognized by the government to assert that the individual has met their unique requirements to attain the status, and for that church to maintain a record as such.
What is Needed for Officiating a Marriage?

State laws govern the rights of individuals to perform a legal marriage. These rights and abilities can vary from state to state, however. Many states require the person who performs the marriage ceremony to present proof of their legal ability to conduct the ceremony. This is usually in the form of a document that the religious order has conferred upon the minister or priest. In these states, the minister must register with the local marriage authority before officiating at a marriage.
In the case of an individual who has received an online credential, the state could require the presentation of a certificate from the denomination for it to be legally valid. Another possible form of proof that could be required would be a Letter of Good Standing.
The important thing to keep in mind is that while states do require certain credentials for individuals who perform marriages, this is not true for a person seeking to be a minister.