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PEOPLE GROUP PROFILE

The Big Sepik of Papua New Guinea

The Big Sepik of Papua New Guinea, numbering approximately 18,500 people, are No Longer Unreached. They are described as an indigenous ethnic group of Papua New Guinea They are an Indigenous people, with Big Sepik as their ethnic/kinship group and are in the New Guinea people cluster of the Pacific Islander Peoples. Their primary religion is Roman Catholicism. They primarily speak Iatmul.

Photo by Google. (2025). Image generated by Gemini 2.5 Flash: Big Sepik

Fast Facts*:

Affinity Group: Pacific Islander Peoples
Country: Papua New Guinea
People Cluster: New Guinea
Primary Language(s): Iatmul (ian)
Primary Religion(s): Roman Catholicism
Population: 18,500
Strategic Progress Index (SPI): No Longer Unreached
Global Status of Evangelical Christianity (GSEC): 5% or Greater but Less than 10% Evangelical
People Group ID: PG009782
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Pray for the Big Sepik of Papua New Guinea

Join others around the world in praying for the lost to be saved, the gospel to advance, the global Church to grow, and for laborers to be sent out and sustained in the harvest.

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Dig Deeper (Religion):

Primary Religion: Roman Catholicism
Religious Affiliation: Christianity

73%
%
Roman Catholicism Adherents

Dig Deeper (Language):

Primary Language: Iatmul
Language Family: Ndu

65%
%
Iatmul Speakers

Media Resources in Iatmul:

Films:

No entries found for: Iatmul(ian). Help build some!

Provided by the Jesus Film Project

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Bible Resources in Iatmul:

Provided by Faith Comes by Hearing

Or check out the Iatmul bible at Bible.com

Linked from YouVersion

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Explore Lostness and Next Steps

Unengaged and Unreached

Strategic Priority Index (SPI): Unengaged and Unreached (SPI: 2), which means there are less than 2% evangelical Christian populations among which there are no known efforts focused on establishing self-sustaining churches consistent with evangelical faith and practice.
Lostness Priority Index (LPI): Marginally Reached People Group, (LPI: 4), 3% to 6% Evangelical.
Global Status of Evangelical Christianity (GSEC): 5% or Greater but Less than 10% Evangelical (GSEC: 5), this people group is greater than or equal to 5% evangelical

Next steps for the Big Sepik:
Begin signifcant prayer and fasting for this group
Send cross-cultural teams to discover and research this people group
Begin gospel seed sowing and church planting among this group

SPI: Unreached yet Engaged

The Big Sepik are Engaged yet Unreached, which means there are less than 2% evangelical Christian populations but there are sustained efforts at establishing self-sustaining churches consistent with evangelical faith and practice.

Next steps for the Big Sepik:
Continue prayer and fasting for this group
Continue gospel seed sowing and church planting among this group
Begin training up local leaders to lead and develop strategies to reach their own people

SPI: No longer Unreached

The Big Sepik are No Longer Unreached, which means there are more than 2% evangelical Christian populations and there are churches consistent with evangelical faith and practice. There is still more to be done among them.

Next steps for the Big Sepik:
Empower local believers to begin praying for their own people
Continue gospel seed sowing and church planting
Encourage local leaders to being leading church planting strategy and looking for Unreached and Unengaged groups nearby

Pray specifically for the Big Sepik of Papua New Guinea

The Lord is a stronghold for the oppressed, a stronghold in times of trouble. And those who know your name put their trust in you, for you, O Lord, have not forsaken those who seek you.
readPsalm 9:9-10

Pray that God will help those who are oppressed and without hope to hear the good news of Jesus and trust in Him, for He has never forsaken those who seek Him.

Declare his glory among the nations, his marvelous works among all the peoples!
readPsalm 96:3

Pray for people to hear and believe the good news of Jesus and joyfully share it with their family and friends.

I give them eternal life, and they will never perish, and no one will snatch them out of my hand.
readJohn 10:28

Pray that as people place their faith in Christ, they will have assurance of eternal life, knowing that no one can snatch them out of the loving hand of Jesus.

For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek.
readRomans 1:16

Pray that God will raise up sons and daughters who, like Paul, will be bold to share the gospel across cultural barriers so that many might receive salvation.

Big Sepik Across Countries (ROP3 - 101423) reported in the following countries:

To download a comprehensive people group list in spreadsheet form, visit our Research Data page.

Peoplegroups.org relies on updates from the field and other organizations for much of our data, so if you have any updates, please contact us. We use various international naming standards. For a list of these standards and fields, visit our Definitions page.

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