Christening - what exactly does a Godparent have to promise to do / be? I have been asked to be a godparent to my nephew.  However, I'm not a Christian.  In a Church of England ceremony, what exactly is asked of the godparents?
In the Church of England you need to be able to answer the questions asked of godparents truthfully and sincerely:


  Parents and godparents, the Church receives these children with joy.
  Today we are trusting God for their growth in faith.
  Will you pray for them,
  draw them by your example into the community of faith
  and walk with them in the way of Christ?
  With the help of God, we will.
  
  In baptism these children begin their journey in faith.
  You speak for them today.
  Will you care for them,
  and help them to take their place
  within the life and worship of Christ's Church?
  With the help of God, we will.


Those may not be too bad: even a non-Christian theist might pray for a child and help them take their place in the Church, and support them in their pilgrimage of faith.

The next set of questions might be more of a challenge to a non-Christian.


  Do you reject the devil and all rebellion against God?
  I reject them.
  
  Do you renounce the deceit and corruption of evil?
  I renounce them.
  
  Do you repent of the sins that separate us from God and neighbour?
  I repent of them.
  
  Do you turn to Christ as Saviour?
  I turn to Christ.
  
  Do you submit to Christ as Lord?
  I submit to Christ.
  
  Do you come to Christ, the way, the truth and the life?
  I come to Christ.
  
  [Common Worship text]


In my [former] Church of England parish, a non-Christian would be advised to think seriously about whether he could sincerely answer these questions, and to consider whether he might do more service to the child’s faith by acknowledging how serious they are, by refusing the invitation in conscience.