By sāyujya-mukti the impersonalists mean relinquishing one's identity, or individuality. This is nothing less than spiritual suicide. In this regard, I reproduce Dr. Radhakrishnan's comment on the Bible:
The doctrine of the Incarnation agitated the Christian world a great deal. Arioes maintained that the Son is not the equal of the Father but created by Him. The view that they are not distinct but only different aspects of one Being is the theory of Sabellius. The former emphasized the distinctness of the Father and the Son and the latter their oneness. The view that finally prevailed was that the Father and the Son were equal and of the same substance; they were, however, distinct persons. ("Introductory Essay," p. 35).
These words vaguely describe the philosophy of "simultaneously one and different"; therefore we acknowledge it. Jesus, the son of God, is a jīva, a separated part of the Supreme Godhead. But the jīva is also spiritual, and hence Jesus is qualitatively the same as the Supreme Lord. But the son can never be equal to the Father in all respects; that is to say, the jīva is never on the same platform as the Supreme Lord. Also, all the jīvas are separate individuals. And just as each jīva is a unique personality, so God is also a unique personality, but the difference is that He is absolute. By describing the Lord as impersonal and formless, one loses sight of His perfect wholeness.