Fourth question: "Where does the spiritual life lead us? How should people recognize whether we do take birth in our next life or not?" Answer: Spiritual life leads us to our original constitutional position free from all designations. This is explained in the Bhagavad-gita as brahma-bhutah status. This brahma-bhutah status means free from all anxieties, without any hankering or lamentation. At that stage only, one can think of universal brotherhood. And the next stage is to be engaged in pure Krishna Consciousness, and thus gradually be transferred to the spiritual world where there is eternal life full of bliss and knowledge.
In other words, the spirit soul, when he is fully liberated from material contamination or designation, he no longer transmigrates to another material body after death. He is transferred to the spiritual world for eternal residence in one of the spiritual planets known as Vaikunthas. The abode of Lord Krishna is the highest Vaikuntha planet, known as Goloka Vrindaban.
People must understand intelligently that they are transmigrating from one body to another at every moment. The body is dying at every moment, and the soul is transmigrating to another body at every moment—this is medical fact. The blood corpuscles are changing at every moment and new corpuscles are taking their place. The old order changes, yielding place to the new. This is going on continually. In this way, the soul is transmigrating from baby body to child body, from child body to boy body, from boy body to youth body. So, at the end, when the material of the body does not act very nicely, the soul has to take another material condition of body, giving up the present one.
The body is changing, but the soul is there. Everyone of us can remember our childhood body or past body. That past body is no longer existing; but I am existing now and I existed in the past, and therefore, I must exist in the future in spite of change of body. These things are nicely explained in the Bhagavad-gita, and we should take advantage of this knowledge.