Rebirth

As discussed in birth and death post, there is no identity left after death. This also means that there cannot be any rebirth, as commonly understood, where Mr. X die today and is born as Mr. Y tomorrow. I think when Mr. X die, his atoms dissolve into the universe. Some of those atoms may be used in Mr. Y, some in Mr. Z and so on. But there is no one-to-one relationship between Mr. X and any other Mr. that comes after him.

What rebirth refers to in Gita and other Vedantic literature, in my understanding, is similar to heaven and hell, which are all experienced in this single life. When you enter into one state of mind (good or bad), you are in a particular life (heaven, hell or earth depending on what the state of mind is). When that state of mind changes drastically, it is like going through intermediate deaths and births, and can totally change the life you are living.

There are multiple references to rebirth in Gita, and they are all explained by this description.

6.41- 6.45 Rebirth (of a yogi) and accumulation of knowledge over many births. The knowledge can be accumulated at different periods in your life and doesn't go away.

8.5 - 8.6 Whatever state of being one remembers at death, O son of Kunti, that state he will attain without fail. I think death here means the end of intermediate phases of life.

8.24 - 8.25 One who passes away in light does not come back. (light here may represent knowledge). One who has attains the absolute knowledge becomes free from frequent changes of state of mind.

14.14 - 14.15 Depending on in which Guna (sattva, raja, tamas) one dies in, he takes birth accordingly.