Theology matters. Good Biblical teaching should be at the core of every Gospel magic performance and this can be easily overlooked by the novelty of medium.
So where do we begin? The Gospel magician should at the very least begin with their own Biblical knowledge. Do you read scripture regularly for yourself? To help you do this there are literally thousands of Bible Reading aids out there ranging from 'Read through the Bible in one year Bible Editions', through to devotional guides such as 'Every Day with Jesus'. Then there are those things specific to our own denomination. I am an Anglican so I use the daily lectionary as my starting point for reading scripture regulalrly and I preach from it every week. Whatever we use - the point is to read scripture regulalrly.
Secondly there are thousands of Christian books which offer commentaries on scripture or highlight themes in scripture. Some of my favourite authors include Philip Yancey, John Stott, John Ortberg, William Barclay, and Rowan Williams.
Thirdly, read Christian journals and magazines for Biblical teaching, knowledge and insight into Christian issues which will relate to your Gospel magic. Christianity Today is a fantastic online resource with many articles which engage with theological issues. Others I read include
http://www.churchtimes.co.uk/ which is the Church of England newspaper, and newfrontiers magazine. Again the point is that there are zillions of resources out there to give us a better informed faith. The Gospel Magician should be growing by reading, reading and reading.
A real challenge would be to do some proper study, either through an online course or through a seminary or Bible school. As Gospel magicians we should do everything to make sure that we are informed and accurates in our presentation of the Christian message.
Finally there is the in house publication of the Fellowship of Christian Magicians which include 'Voila' (FCM Europe) and the 'Christian Conjurer' which include well thought our presentations combining Bible teachings and Gospel Magic illusions.
Go for it and get reading.