Matthew 13:13

Jesus restated His reason for using parables in terms of human perception rather than divine intention (cf. Matthew 13:11-12). The unbelievers were not able to understand what He had to reveal since they had refused to accept more basic revelation, namely, about Jesus and the imminence of the kingdom. The parables do not just convey information. They challenge for a response. The unbelievers had not responded to the challenge Jesus had already given them. Until they did they were in no condition to receive more truth.