A lay leader is a member of the laity

Laity

In religious organizations, the laity comprises all people who are not in the clergy. A person who is a member of a religious order who is not ordained legitimate clergy is considered as a member of the laity, even though they are members of a religious order .In the past in Christian cultures, the...

 in any congregation who has been chosen as a leader. Since lay leadership is not an ordained

Ordination

In general religious use, ordination is the process by which individuals are consecrated, that is, set apart as clergy to perform various religious rites and ceremonies. The process and ceremonies of ordination itself varies by religion and denomination. One who is in preparation for, or who is...

 clerical office, the lay leader's responsibilities vary according to the particular tradition to which he or she belongs. Some organizations do not allow the lay leader to give sacraments for example, but do allow them to perform most other portions of the service that are normally the responsibility of the clergy (e.g. giving sermons when the regular clergy are on vacation). The Assemblies of God official position paper on Ordination states, "When necessary, the laity can perform all of the functions of ministry except those for which the State requires an ordained minister."

A lay leader in a Christian congregation, other than the professional paid minister, is one who volunteers to lead a ministry.

In The United Methodist Church the lay leader refers to the principal layperson in a local church, district or Annual Conference

Annual Conference

An Annual Conference in the United Methodist Church is a regional body that governs much of the life of the "Connectional Church." Annual conferences are composed primarily of the clergy members and a lay member or members from each charge . Each conference is a geographical division...

 who represents and leads the laity in ministry. It is an elected position, and the lay leader will serve on all church committees.

Various titles are used for lay leaders in different religious organizations, including lay preacher; lay reader

Lay Reader

A lay reader is a layperson authorized by a bishop of the Anglican Church to read some parts of a service of worship. They are members of the congregation called to preach or lead services, but not called to full-time ministry.Anglican lay readers are licensed by the bishop to a particular parish...

 (in Episcopal churches); lay speaker

Lay speaker

A lay speaker is a position in the United Methodist Church for the laity. Technically, a lay speaker is a “member of a local church … who is ready … to serve the Church.” Generally, lay speakers are leaders in the United Methodist Church on local, district, and conference levels...

 (in the United Methodist Church, USA); local preacher (in the UK Methodist Church

Church Body

A local church is a Christian religious organization that meets in a particular location. Many are formally organized, with constitutions and by-laws, maintain offices, are served by pastors or lay leaders, and, in nations where this is permissible, often seek seek non-profit corporate status...

 and the Uniting Church in Australia); Reader (in the Anglican Church); and deacon

Deacon

Deacon is a ministry in the Christian Church that is generally associated with service of some kind, but which varies among theological and denominational traditions...

, though this last title can also refer to an ordained ministry.

Responsibilities

The following list gives examples of things lay leaders may be responsible for

• acting as ushers
• making announcements
• reading scripture
• giving guest preaching sermon
  Sermon
  A sermon is an oration by a prophet or member of the clergy. Sermons address a Biblical, theological, religious, or moral topic, usually expounding on a type of belief, law or behavior within both past and present contexts...
  
  s
• conducting a complete service