John Allen Chau travelled to North Sentinel Island in the Indian Ocean and was attacked between 16th-18th November.
He studied at Oral Roberts University, who train people in how to share Christ across the world and was keen on sports outreach.
William Wilson, President of ORU missions, said: "We are not surprised that John would reach out to these isolated people to share God's love".
John Chau wrote to his parents before his death: "You guys might think I'm crazy in all this, but I think it's worth it to declare Jesus to these people.
"Please do not be angry at them or at God if I get killed. Rather, please live your lives in obedience to whatever he has called you to and I'll see you again when you pass through the veil."
Global mission society All Nations gave a statement about Chau's death. All National International Executive Leader Dr Mary Ho said:
"We have been in contact with John's family and ask all to join us in praying for his family and friends during this time. We have been in contact with the U.S. State Department and continue to cooperate fully with all international, national and regional officials."
All Nations said he had 'studied, planned and trained rigorously since college to share the gospel with the North Sentinelese people.
Dr Ho added: "John was a gracious and sensitive ambassador of Jesus Christ who wanted others to know of God's great love for them,
"As we grieve for our friend, and pray for all those who mourn his death, we also know that he would want us to pray for those who may have been responsible for his death.
"We remember too, how throughout church history, the privilege of sharing the gospel has often involved great cost. We pray that John's sacrificial efforts will bear eternal fruit in due season."
