Is the world an illusion?

The Mayavadi philosophers say that this material world is mithya, false, and that one should therefore not bother about this mithya creation (brahma satyam jagan mithya). But this is not correct. Here it is said, satya-krt: whatever is created by the Supreme Personality of Godhead, satyam param, cannot be called mithya. The cause of the creation is satya, true, so how can the effect of the cause be mithya? The very word satya-krt is used to establish that everything created by the Lord is factual, never false. The creation may be temporary, but it is not false.

Srimad Bhagavatam 7.1.12 purport