After reading this question, I will use the knowledge gained in class to answer it along with the way of knowing faith, which takes a big part on the state “believe in”. But before we start answering it, we should know what believe means.
The term believe differs from one culture to another but it will always have a really common definition with knowledge, as Plato stated (ca. 428-ca. 347 BCE) “Knowledge is true, justified belief”.
Although believes are very subjective, faith takes part in this process, working together with the other ways of knowing. Believing is a process that only you, as a person can do. In there, your emotions, your feelings and memories combine and give a result, the fact that you believe.
When someone says ” I believe in…” they are actually saying that they believe in someone or something to get a goal achieved, but that only senses can perceive and this means they have a mass and occupies space. As many people when they are going to take an exam they say to themselves: “I believe in myself” because they “exist”. The preposition “in” means that the existing object the person trusts in is not an idea nor an image.
Meanwhile when we say “I believe that…” means the other way around. Here you can state ideas, images and opinions. Not because they do not exist, but because the speaker thinks that they do. For this statements you wouldn’t need any proof required while in the previous one you would. Continuing with the example of a student taking an exam they can perfectly say “I believe that luck exists”, and you can not snatch the arguments from him, due to the fact that he or she believes that luck exists.
Although these two terms are used mutually they present two different ideas and by discussing the knowledge issues concerned with the two terms one can understand the vital differences between them.