Pentecostal denominations began to form following the exp. of the baptism in the Holy Spirit and glossolalia phenomenon of 1907 in Los Angeles. The Assemblies Of God (AOG) one of the largest, formed in 1914, and the Pentecostal Assemblies Of Canada (PAOC) in 1919, as well as numerous other Pentecostal associations.
These Pentecostal associations (considered ‘classical Pentecostal), remained fairly tight knit within their own particular organizations, until recent years, creating global para Pentecostal conferences within their various classical Pentecostal camps.
Ecumenism – Application
Ecumenism, movement or tendency toward worldwide Christian unity or cooperation. The term, of recent origin, emphasizes what is viewed as the universality of the Christian faith and unity among churches. The ecumenical movement seeks to recover the apostolic sense of the early church for unity in diversity, and it confronts the frustrations, difficulties, and ironies of the modern pluralistic world.
The word ecumenism is derived from the Greek words oikoumenē (“the inhabited world”) and oikos (“house”) and can be traced from the commands, promises, and prayers of Jesus. After the International Missionary Conference held at Edinburgh in 1910, Protestants began to use the term ecumenism to describe the gathering of missionary, evangelistic, service, and unitive forces. During and after the Second Vatican Council (1962–65), Roman Catholics used ecumenism to refer to the renewal of the whole life of the church, undertaken to make it more responsive to “separated churches” and to the needs of the world.
The possibility of an ecumenical approach, in the modern sense, to Christianity increased, somewhat ironically, in the 17th and 18th centuries, when English dissenting sects and Pietist groups in Europe began to promote evangelistic, revivalistic, and missionary endeavours. This, along with the simultaneous effect of Enlightenment thought, broke down many of the traditional foundations that supported separate church structures. Other breakdowns in the traditional understandings of church unity led to new possibilities for experimentation in the 19th century. The separation of church and state in the United States signalled the need for civility and respect for religious rights in a land of many religions. The sending of Protestant missionaries at the beginning of the 19th century revealed the possibilities of cooperation across denominational lines at home and brought to light the scandal of competition and conflict among Christian denominations abroad.
Early 20th-century ecumenism derived impetus from the convergence of three movements: international Protestant missionary conferences, beginning with the Edinburgh Conference (1910) and taking shape as an institution in the International Missionary Council (1921); the Faith and Order Conferences on church doctrine and polity, commencing in the conference at Lausanne (1927); and the Life and Work Conferences on social and practical problems, beginning with the Stockholm Conference (1925). In 1937 at the Oxford Conference of Life and Work, proposals were drawn up to unite churches with Faith and Order. To this end, the World Council of Churches, a consultative and conciliar agent of ecumenism, working with national, denominational, regional, and confessional bodies, was inaugurated in Amsterdam in 1948. The International Missionary Council joined the World Council of Churches in 1961.
Evangelical Protest To Nominal Ecumenism
Protest movements against the developments that led to and continued in the World Council of Churches have produced an ecumenical convergence of their own. Most participants in this convergence prefer to be called “evangelical.” In the United States the National Association of Evangelicals was formed in 1943, in large part to counter the Federal Council of Churches, which began in 1908 and reorganized as the National Council of Churches in 1950. Evangelicals have many organizations that operate on an international level to channel specific cooperative energies.
Some of the good intentions of ecumenism were, facilitating joint missionary efforts, humanitarian works, promoting unity, acceptance of other christian organizations.
Liberalism was a major stumbling block in covenantal statements of belief and unity.
The Lausanne Movement – Another Gospel
Ecumenism: Another Gospel provides evidence of how the Lausanne Movement, influenced by the compromised ideas of new evangelicalism and the liberal theology of Fuller Seminary, has moved away from sound biblical Christianity. The third Lausanne Congress in Cape Town (2010), which claimed to be the largest gathering of church leaders in history, proclaimed its love for the world’s poor, dealt with the role of women in church leadership, expressed concern about climate change, emphasised the importance of the arts in worship, and promoted social justice. Top of the agenda, however, was the concept of storytelling the Gospel and an oral Bible.
The Lausanne Movement is a worldwide network committed to the cause of ‘world evangelization’, founded by two of the biggest names in Christianity, American evangelist Billy Graham and British theologian John Stott. The Movement, which was established in 1974 in Lausanne, Switzerland, has introduced a new way of doing evangelism that combines social activism with the message of salvation
– called ‘evangelization’. Over the years the ecumenical ambitions of the Movement have become increasingly obvious, as many within it seek to work closely with the Church of Rome.
Of concern is the influence that Lausanne’s unsound teaching is having on churches in the developing world and on most missionary organisations worldwide. Well known theologians from the West, supported by Fuller Theological Seminary, are using the Lausanne platform to propagate a social agenda that compromises the Gospel of Truth.”
(Extra resource Pentecostals and Lausanne)
As the evangelical ecumenical forums presented problems of their own, the burgeoning Pentecostal movement was about to face theirs as well.
To follow the Pentcostals skip below ‘Fascinating Facts’
FASCINATING FACTS- ECUMENICAL MOVEMENT
The Modern Ecumenical Movement is Born-The CIA?
“Ecumenism has come to mean “reducing all elements of faith to the lowest common denominator.”
THE WORLD CHRISTIAN MOVEMENT
EVANGELISM VS. EVANGELIZATION
By Albert James Dager
Pentecostalism – Ecumenism – Issues
With so many variations of ‘Pentecostalism,’ ecumenism amongst Pentecostals faces as many or perhaps more issue than evangelicals in general, with the arrival of ‘post denominational’ Pentecostals, Neo Pentecostals or (Charismatics in general) with varying beliefs and perspectives even within this movement.
The Charismatic church’s affinities and affiliations formed much of their ‘ecumenical unifying,’ establishing large Christian universities, such as Melodyland School Of Theology and Fuller Theological Seminary.
Various Classical Pentecostal camps began to entertain some interest in various evangelical, ecumenical efforts, even Lausanne.
More recently classical Pentecostals have opened more lines of communication with ‘Charismatic Pentecostals’ and both embracing once resistant relationships with other ecumenical organizations.
Herein lies a major ecumenical problem, that is first of all recognized in the ‘Fascinating Facts Of Ecumenism’ above.
Secondly, the Charismatic movement was a seed bed of growing errors, fed from the ‘Latter Rain’ movement. Paradoxically, the very ‘Latter Rain’ errors that the AOG rejected in 1948, have now been, thro’ ecumenical efforts, affiliated and aligned with, thro’ the likes of ‘Empowered21’ and other unBiblical aberrancies such as ‘contemplative prayer,’ and other corrupted ‘prophetic’ practices.
Many errors and aberrancies that have been growing within the ‘charismatic/prophetic movement’ are now being embraced by more long standing classical Pentecostals.
Empowered21 – ‘Spirit empowered’ Ecumenism
Empowered21 is an ecumenical effort to align ‘Spirit empowered’ christians in united efforts to influence and propagate ‘charismatic Pentecostal’ beliefs, many of which are clearly ‘Latter Rain’, esp. as they are propagated by aberrant, and heretical charismatic figures.
Empowered21 has many on it’s board, as well as yearly speakers, that could be identified as NAR affiliates. Pentecostal ecumenism has come full circle, not just the ‘charismatics’ who have embraced liberal ecumenism, including Catholicism, but long standing classical Pentecostal denominations.
Here are some more startling facts about the ‘Empowered21’ Pentecostal ecumenism.
“NAR heavyweights Bill Johnson and “prophet” Cindy Jacobs are in E21 Leadership,  and Jacobs herself is a high profile teacher/speaker at the conference.
Cindy Jacobs was not only a featured speaker (along with George Wood and four others) at the Amman, Jordan event, but is the co-chair of the Jerusalem2015 Prophecy and The End Times Ministry Track. 
Here is a good example why Christians should be very concerned that she has such prominence in E21. Several years ago, speaking before a rapt audience, Cindy Jacobs put this NAR spin on the Lord’s Prayer:”
According to Jacobs:
“…and God showed me [The Lord’s Prayer] was a prayer and every part of the prayer is an element on how to reform and transform a nation.” 
The Lord’s Prayer “is the prayer of intercession that will help bring into manifestation the original Genesis Mandate to fill, subdue, multiply and have dominion in the earth.” 
“So we have authority to reverse the Genesis curse of poverty and death. Not only do we have the power to do so, we have the mandate. You have to understand this.” 
“This was our commission in the Garden and it never changed…and so, because we didn’t understand our commission sin came into the world and it began to deteriorate the ability we had to steward the earth.” (emphasis mine) 
“Dominion theology consistently usurps Millennium promises and tries to apply it to the present age in order to justify its agenda to transform society into the Kingdom of God on earth,” writes apologist Al Dager. 
George Wood General Superintendent AOG-
So here we have the leader of the AOG USA, co-chairing a global Pentecostal ecumenical organization ‘Empowered21’ who’s leadership is filled with NAR leaders, clearly teaching ‘Latter Rain’ doctrine, including the ‘7 mnt. mandate,’ of ‘Dominionism.’
The PAOC – Of Canada Are Following Suit
Pentecostal youth are being channeled into E21 in all of it’s influences.
Classical Pentecostalism has gone the way of syncretic ecumenicism
The goals may seem noble, and righteous – to resist unloving, standoffish. Many will criticize, and misunderstand the concerns expressed, but where is this headed? Even below are more ex.’s of the spiritual compromises Pentecostals have been making. What was unanimously rejected over 70 years ago by Pentecostal leaders, is now welcomed ‘into the fold.’
Post-Pentecostalism has arrived!
Sadly! The new Pentecostal ‘Trojan Horse’ has been welcomed.
No one can think they are safe within their ‘denominational walls’!
Everyone must examine where they are, their spiritual environment, asking, “Am I safe?”
‘Historic Reconciliation Between Pentecostal Assemblies Of Canada and Independent Assemblies Of God International.” (a ‘Latter Rain’ affiliate)
AOG – George Wood Superintendent Justifies Contemplative Prayer
Dr. George Wood, General Superintendent of AOG joins Leonard Sweet