What does “mainline” mean?
“Mainline” is not a word the Bible uses for churches. It developed as a way of describing several large, older Protestant denominations in America, many of which once had prominent congregations along major railway lines and in leading cities. People now often use it more broadly for churches with historic roots, formal denominational structures, and a generally moderate or progressive public identity.
The label can be useful, but it can also blur important differences. A congregation’s name tells you something about its heritage, yet it does not tell you everything about its worship, teaching, care for people, or love for Christ. The New Testament puts the focus elsewhere: believers belong to Christ and are called to serve one another as parts of one body (1 Corinthians 12:12-13).
For as the body is one, and hath many members, and all the members of that one body, being many, are one body: so also is Christ.
Which denominations are usually included?
There is no single official list, but people commonly mean the Episcopal Church, the United Methodist Church, the Evangelical Lutheran Church in America, the Presbyterian Church (USA), the United Church of Christ, American Baptist Churches USA, and the Christian Church (Disciples of Christ). Some lists also include smaller historic bodies or particular regional churches.
These churches do not all organise themselves in the same way. Episcopalians have bishops, Presbyterians are led through councils of elected elders, Methodists use conferences and bishops, while Baptist and many Disciples congregations place strong emphasis on local church leadership. Their worship can range from liturgical services with set prayers to simpler services centred on preaching, prayer, singing and communion.
What do they generally share?
Mainline churches are Protestant, so they trace their roots through the Reformation rather than Roman Catholicism or Eastern Orthodoxy. They usually affirm the central place of Scripture, worship the Triune God, baptise, celebrate the Lord’s Supper, and confess Jesus Christ as Lord. Christians have long been urged to hold firmly to Jesus as the foundation, rather than building their faith around personalities or factions (1 Corinthians 3:11).
Many mainline denominations also have a strong tradition of mission through schools, hospitals, relief work and advocacy for people facing poverty or exclusion. Caring for practical needs is not a substitute for the gospel. It is one way Christians seek to live out love for their neighbour (James 2:15-17).
For other foundation can no man lay than that is laid, which is Jesus Christ.
Why do Christians sometimes disagree about them?
Within and between mainline denominations, Christians differ on questions such as baptism, the role of women in ministry, sexual ethics, church leadership, the authority and interpretation of Scripture, and how faith should shape public life. These are real matters, and they deserve honesty rather than stereotypes. Some Christians value the mainline emphasis on historic worship and social responsibility. Others are concerned that particular denominations or congregations have moved away from what they believe Scripture teaches.
If you are looking for a church, it helps to visit, listen carefully, and ask direct questions. Does the church speak clearly about Jesus, read Scripture seriously, pray, practise love, and make room for repentance and growth? The Bereans were commended for checking teaching against the Scriptures (Acts 17:11). Jesus also said that his followers would be recognised by their love for one another (John 13:35).
These were more noble than those in Thessalonica, in that they received the word with all readiness of mind, and searched the scriptures daily, whether those things were so.