Islam and Christianity, were both formed from Judaism. Whereas Buddhism derived from Hinduism (the most ancient of these religions). So the you can find many common similarities in all of these religions, but only at a few at a time.
- every religion is created by humans and that to teach good, so a common thing is humanism
- They all believe in 'good people' and 'bad people' and that being 'good' will benefit either oneself and/or the outer community
- They all have an idol, 'being' or idols of their worship: Buddha (Buddhism, Allah (Islam), God (Judaism, Christianity), Saints (Christianity), deities or Brahma (Hinduism), Mohammed (Islam), Moses (Judaism, Christianity), Jesus (Christianity) etc.
- They all have teachings common to the earliest of the group - Hinduism
- They all have a say in life after death
- They all have 'holy men' ex. priests, monks, etc.
- They all have sacred places