Here is a great "gospel magic" lesson. It also is just a good trick for the non-Christian audience.

2 Corinthians 5:17 Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new.

This is a very simple, yet very magical effect and a very visual demonstration of a Bible truth. A lot of folks claim to be Christian, but the Bible is very clear, when Jesus comes in, it is life-changing.

Effect: An orange placed in a bag magically transforms into an apple.

Needed: 1 paper bag, 1 apple, 1 Navel orange

Performance:
Peel the orange very carefully by slicing with a knife. A large navel orange seems to be the best for this. Eat the orange. Cover the apple with the orange skin. The more care you take peeling the orange, and perhaps even glueing the skin back together along the seams, the more realistic the effect.
Show the paper bag to be empty. Show the orange, place it into the bag. Read 2 Cor 5:17, reach into the bag, remove the apple. Crush the bag and orange peel together to demonstrate that the bag is empty.
Very magical.