Answer
Don't try to convince them.
Krishna Himself does not force anyone to accept Him, so why should we?
Every living entity has free will. There are millions and billions of souls who are simple-hearted and genuinely want to return to Godhead. Preach to them instead.
Why spend time trying to convince those who have already firmly decided that there is nothing beyond impersonal Brahman and that individuality is ultimately false?
The Lord resides in everyone's heart. He permits even impersonal realization. However, there is no substitute for a living entity consciously choosing to surrender to Krishna as the Supreme Personality of Godhead.
That decision must come from the individual soul, although it is greatly influenced by the association of pure devotees.
Just as all of us received the association of Srila Prabhupada and pure devotees and became Vaishnavas, we now understand these subjects from the Vaishnava platform.
From this platform, we can properly understand Mayavada philosophy and see where it fits. Mayavadis interpret bhakti-yoga within the framework of impersonal Brahman, while we understand Brahman within the complete understanding of the Absolute Truth.
They also accept many of the same Vedic scriptures, but they interpret them as referring to another level of reality, or ultimately as illusion.
We do not say that the individual living entity is an illusion.
Existence itself is not an illusion. Illusion means misidentification.
For example, a robot is real. Similarly, this body is real—it exists. The illusion is thinking, "I am this body."
Consider a car. The car is real. If you know that you are the driver and not the car, there is no illusion. The illusion begins when you identify yourself as the car.
Likewise, the body is a real, temporary, ever-changing reality. It is not the ultimate, absolute reality, but it is not false. The mistake is identifying the self with the body rather than understanding oneself to be the eternal soul.
