A non-denominational church can be thought of as a religion that has its own beliefs, but does not have an associated body of beliefs. It does not, however, follow the teachings and practices of any particular denomination, such as Roman Catholicism or Mainstream Protestantism. A non-denominational church can also be thought of as a "lack of a religion" - this is similar to saying that a society is devoid of a legal system or a government. Non-denominational churches often prefer a spiritual type of worship, and do not have as many fundamental beliefs as some other kinds of churches do.
A non-denominational church could be thought of as being any number of things. There are many definitions and classifications for what would qualify as a non-denominational church. For example, the Associated Church of Churches puts out a list of characteristics that they consider to be non-denominational, including beliefs that are not consistent with the traditional definitions of religion. Their list includes traditional definitions of God, Jesus, sin, heaven, hell, creation, man, and the Word of God. The main emphasis of the teachings at the church in Washington DC is that all these aspects are found within the Bible, and that one must incorporate these teachings into their lives in order to be saved.
An additional non-denominational church would be a nondiscological one, which would include a belief that there is no entity or person known as God, but God is still involved in the affairs of this earth. Most people who belong to this kind of church are active in the community but have no formal ties to any church. They may not attend regular nondenominational church DC services, but whatever their personal beliefs are, they tend to keep them to themselves and keep their faith private.
There is also a category of non-denominational churches that are similar to what we call "mainline Protestants." These are the catholics and the reformed or mainstream Christians. They do not claim to have special beliefs or even a special connection to the religion in question. Instead of adhering to the teachings of the Holy Bible, they tend to follow what the catholic church preaches. This group of non-denominational Christians tends to be somewhat passive regarding the theological issues of the bible and tends not to put much weight on the concept of a Holy Communion.
Besides these two main categories there exist many others. There are several types of non-denominational churches such as Advent, Pentecostal, and Spirit Meeting. All of these types believe in the same fundamental beliefs of Christianity. The main difference between them is that the catholic churches tend to be more authoritarian in their beliefs and practices while the other kind of church tends to be more flexible in their views and practices. While the differences between the two types of non-denominational churches can sometimes seem extreme, there are also some points of similarity. For instance both of the main branches of the catholic Church, the Roman Catholic Church and the Eastern Orthodox Church teach the doctrine of salvation through grace through the atonement of Jesus Christ.
When attending a non-denominational church, it is best to know how large the overall congregation is and how often these types of congregations meet. If you go to a church where there are many people but not a lot of children or teenagers then chances are you will not get the chance to hear the latest discussion on the biblical issues. As I stated above, this can be one of the biggest drawbacks to many non-denominational churches. If this is the case then you may want to stick with a smaller more private more personal church where this is not an issue. Check out this related post to get more enlightened on the topic: https://www.britannica.com/topic/church-Christianity.
