What does it mean to "believe in" someone or something?

Question

John 3:16 (New International Version) For God so loved the world that he gave his one and only Son, that whoever BELIEVES IN him shall not perish but have eternal life. [caps added]

Does it simply mean to acknowledge/accept the existence of that person or thing? What is the difference between believing in Jesus and believing in King Tut?

Answer 1

A very reasonable question.
First you must draw a distinction between fact and belief. Fact is something that can be proven to be true. That King Tut existed is a fact. That Jesus of Nazareth existed is also a fact. These facts do not require belief because belief is an acceptance without proof. Belief is faith.
Jesus of Nazareth is the Christ and also called the Son of God. God took on flesh and came to dwell among men so that He could experience life as men did, suffer as men suffer and then die as men die in order to pay the price of sin once and for all. There is no proof of this, that is why it is accepted on faith. That is what it means to "believe in" something.
As for King Tut, we know he existed, and if you wish, you can believe that he had a heart shaped tattoo on his forehead. There is no proof of it, but you can still believe in it. On the other hand, maybe he did.
Bottom line: To believe in something is to accept it to be true of faith. With Jesus, it is to accept who and what He is (God incarnate), why He came (to save us from sin), and what He offers (eternal life and salvation).
Salvation is a gift. It can not be earned. But that gift requires sincerity. To obtain the gift, one must reject sin by repentance and acknowledge Christ for what He is and ask His forgiveness. Then out of love and obedience, a Christian will follow Christ's teachings and keep His commandments.