There are several different terms representing specific forms of belief or disbelief. One of the things that makes the terminology somewhat complicated is that the modern English term "belief" actually can refer to two different concepts, belief in the existence of a god and worship of that god.
The term "atheist" is used to refer to people who are absolutely certain that no gods of any type exist and who also do not worship any gods.
"Agnostic" is the term which applies to people who are not certain about whether gods exist or not or, if they do exist, what their nature might be. These can include people who are undogmatic atheists but also may include religious or spiritual people who believe that it is not possible to have certain knowledge about the nature or existence of gods.
The term nontheistic can apply to a range of people who do not believe in the existence of personal gods and even certain religions such as Buddhism or Unitarian Universalism.
Most people in the modern western world accept that science describes many aspects of the world correctly. This means that they "believe in" science to the degree of believing that certain things stated by certain scientists are correct. No scientist would believe that every single scientific hypothesis ever advanced was correct; in fact, one measure of scientific thinking is that one is constantly checking one's assumptions by means of research and experimentation rather than holding dogmatically to a single set of assumptions. The other sense of belief, namely "worship" or "faith", is one really opposed to scientific thinking.
In philosophy, the belief that all phenomena can be explained by material causes (and thus that there is no explanatory need for a god) is called "materialism".
One group of atheists, sometimes called the "New Atheists", of whom the most notable is Richard Dawkins, do seem, though, to treat science almost as a religion, looking to it for solutions to all the problems of the world.