Why Do So Many Missionaries Leave The Field Early?

According to this video by Global Frontier Missions (GFM), 75% of missionaries leave the field before their first term is up. Why are so many leaving early?

According to this IMB (International Mission Board) article, here are 5 possible reasons:

1. Excitement Without Calling

2. Spiritual Immaturity

3. Poor Health

4. Children's Needs

5. Sexual Sin (Moral Failure)

This article from ChurchLeaders.com suggests that the number one reason missionaries leave is conflict with other missionaries. They say there are five relational challenges that threaten all missionaries:

1. Unmet Expectations

2. Conflict Equation (Lots of sinful people create lots of problems.)

3. Stressful Life

4. Comparison and Jealousy

5. Persistent Sin

What do you think? Is there validity to any of this? Without a doubt, missionaries can greatly benefit from your prayers for them!