Christianity emphasizes that we should be generous, that we should have giving hearts. Charity is a practice that leads to heaven. Jesus said that it is as hard for a rich man to enter heaven as it is for a camel to pass through the eye of a needle. He said this because many wealthy people cannot bear to give things away. They almost always have an ulterior motive. The Rockefeller Foundation is a philanthropic organization, and it has funded many wonderful things, but it is still a tax write-off for the Rockefeller family. If a person gives donations or helps others with ulterior motives in mind, then he is not truly giving. If you are going to give things away, you should do so unconditionally, renouncing and forgetting whatever you give. If your motive for giving is to go to heaven, then your actions are not unconditional.
Once its power is expended, the arrow falls,
Bringing discontent in the next life.
How can this compare to the true door of non-action,
Through which one leaps straight into the Tathagata ground?
A true practitioner does not dwell on the fruit of his actions. After he gives something, he renounces it, and does not think of the consequences. It does not mean he acts rashly, without thinking. Rather, he acts spontaneously, and in accordance with the Dharma; he does not cling to actions or their consequences.
The Buddhist concept of heaven is different from the Christian concept. Christians believe that heaven is eternal; that once you enter, you never depart. According to Buddhism, heaven is still subject to time and change. You can be reincarnated in heaven by merit of donations and good deeds, but it is simply another mortal incarnation. Though your life span in heaven may be millions or billions of years, eventually your time will run out, and you will drop back to the human realm, or even a non-human realm.