To be real, the person is not merely agreeing with the baptism, they are obediently walking eyes open into it and then continuing to walk in that same obedience ever after. It is induction into the perpetual course of the teachings and salvation provisions of the Christ. They need to first believe that Jesus is indeed the Christ or else this baptism is not real. Part of the saving provisions of the Christ is the real Holy Spirit as seen in manifestations such as real genuine speaking in tongues (not glossalia babbling but genuine spiritual language enunciation often with interpretation to benefit the hearers) and God only gives this when the baptism and belief is real and sincere. Hence it is baptism in water and in the Holy Spirit. It sets a person apart and unites them with the living Jesus Christ.
