Answer
Originally, a Union church was made up of two churches of differing denominations that used the same property and owned it jointly (as opposed to one church renting the property from the other and using it for services). In such cases, the term Union church might actually refer to the building or the property. For instance, if a Presbyterian congregation and a Reformed congregation both used and jointly owned a building, how would a person refer to that building? Normally, with a single congregation meeting in one place, the building would be called “the Presbyterian church” or “the Reformed church.” But in the case of two churches with joint ownership of the property, the building would be referred to as “the Union church.” So, instead of people saying, “The meeting will be held down at the Presbyterian/Reformed church,” they would say, “The meeting will be held down at the Union church.”
A Union church would have two (or more) separate pastors and congregations. The concept of having a Union church started in areas where the population was small enough that no single congregation could afford to build and maintain its own building.
In some cases, if one congregation grew, it might move on to its own property, and the remaining congregation(s) would “buy out” the interest of the other congregation. In other cases, the congregations might develop such a working relationship that they decide to fully unite under one name and denomination.
Although the original arrangement is rare today, the name “Union Church” is still in use. In many cases, this term is used by churches that want to emphasize that they are non-denominational and that they welcome and affirm all people regardless of their ethnicity, gender, sexual orientation, individual beliefs, or denominational affiliation. In these cases, the church’s greatest concern may be that people be accepted and affirmed regardless of what the Word of God may have to say on any given topic or lifestyle choice. The name “Union Church” may indicate this approach, but it is by no means certain. The name might be a historical holdover, or it might have been chosen for other reasons. As with any church, regardless of the name, it is important to find out what a Union church believes and how it functions before committing to membership, involvement, and support.