It recently occurred to me that a good answer to questions like this, that is to say, questions which assume there are two possible and reasonable answers when really there is only one, is simply to say as follows. I believe in life. Very frequently the way we frame a question has a bearing on the answers it may have, but if you just cut past the false assumptions that have come up with the question in the first place then maybe you are answering it as it should best be answered by revealing its fundamental invalidity.
Likewise, do you believe in God? What do you mean? God exists. Would you ask do you believe in yourself? Well, some people do, but it's not a serious question. We only think this might be a serious question because our minds have been so knocked out of their natural orbit by wrong thinking and bad education that we can't think straight.
When you think about it, birth and death are events that take place in time but consciousness itself exists always in the now. That is a truism which has become a cliché. But it leads to the thought that, while the form consciousness takes might change, the thing itself remains. So death then appears more like the changing from one state of consciousness to another rather than the termination of consciousness. For it seems improbable that an event that takes place in time can have a permanent effect on the existence or otherwise of something that is essentially timeless.
Therefore to ask if you believe in life after death is a question based on a miscomprehension. If there is life before death, physical death, then there must be life after it too. The real question is what sort of life is this? And the answer to that surely depends on the quality of the consciousness.