Non-denominational is generally used to refer to one of two forms of independence: political or theological. That is, the independence may come about because of a religious disagreement or political disagreement. This causes some confusion in understanding. Some churches say they are non-denominational because they have no central headquarters (though they may have affiliations with other congregations.) Other churches say they are non-denominational because their belief structures are unique.
Members of non-denominational churches often consider themselves simply "Christians". However, the acceptance of any particular stance on a doctrine or practice (for example, on baptism), about which there is not general unanimity among churches or professing Christians, may be said to establish a de facto credal identity. In essence, this would mean that each non-denominational church forms its own unofficial "denomination" with a specific set of tenets as defined by the beliefs and practices of its own congregation.
Individuals who are Christians seeking ordination to perform marriages, are called to organized ministry, want to add "something more" to their counseling practice, or who are just active Christians needing documentation and/or credentials to reach out to needy people there are many organizations which can provide this on the web. Individuals who seek to obtain a non-denominational Christian ordination can do so for free through The Church Of Living Water
In the Presbyterian Church (U.S.A.), ordination exams are given to seminary seniors to ensure that a candidate for ministry is adequately prepared. The four exams include: Theology, Worship and Sacraments, Polity, and Biblical Exegesis (undertaken in either Biblical Greek or Hebrew.)
The first three, respectively, are taken in a proctored setting over the course of two days. The last is given to students at the conclusion of the other three, and is taken home for completion. In addition, all candidates for ministry must pass a fifth ordination exam typically given the first year of seminary called the Bible Content Exam.
Exams are graded by at least two readers on a scale of 1 to 5. 3 is a passing score, and 5 is outstanding. If one reader passes a student, and a second fails that student, a third reader is then called in to make a final judgment.
Special considerations are made for students whose first language is not English, and the exam is regularly administered in Spanish and Korean.
It is common for students to have to take their exams several times before passing. Up to 28% of ordained ministers will have repeated at least one exam. Some, though not all, presbyteries impose a limit on the number of times their candidates may attempt an exam. Others allow for alternative formats. Still, a fair number of students do not pass all of their exams after several tries. It is not unheard of for a candidate to be dismissed from the ordination process after multiple attempts to pass the tests have failed.
In addition, Presbyterian seminarians are required to pass an examination covering the content of the Bible. Practice exams are available here