Heaven (devaloka) is one of the six states beings can take rebirth in, the others being the human realm, the animal realm, the realm of jealous spirits, the realm of hungry spirits and purgatory. Heaven is a realm or state that is primarily pleasant and the lifespan is very long. People who have developed positive emotions to a high degree – kindliness, acceptance, innocence, love – without necessarily being very wise, tend to be reborn in heaven. While heaven is far better than purgatory or the realms of animals, jealous spirits or hungry spirits, the Buddha considered it to be inferior to the human realm. Because their experience is so pleasurable beings in the heaven realm have neither the opportunity nor the encouragement to develop virtue or understanding. And of course, when their lifespan comes to an end (like all states, heaven is impermanent) they will be reborn yet again.
Anyone can get to heaven
Some religions contend that only members of their religion can enter heaven. There is no such teaching in Buddhism. The Buddha taught that anyone from any religion can get to one of the heavenly realms. This is shown in several places in the suttas, including:
“Another person has practiced the making of merit by giving as well as by moral discipline to a high degree; but he has not undertaken the making of merit by meditation. With the breakup of the body, after death, he will be reborn among humans in a favorable condition. Or he will be reborn in the company of the devas of the Four Great Kings.” Anguttara Nikaya 4.241-243
- Buddhism A to Z. Ven. Dhammika, 2007.
- The Complete Book of Buddha's Lists -- Explained. David N. Snyder, Ph.D., 2006.