We began by taking everything Jesus ever said (or was quoted as saying in the Gospels). This turned out to be about 1,000 lines of text. We decided early on that all answers would be given in the ‘vox domini’ or the voice of the Lord.
Then it was a simple matter of linking up every possible to be asked question in the English language with a quote from Jesus. For this task we created two 'training' programs and began to hand match questions and answers. Some of the machine's initial intelligence was able to match questions to answers and our training programs would reward good behavior. Our users continue to reward us for good answers and the machine continues to learn from these responses.
Short Answer: AI and Machine Learning.