Than Jesus cried out, "When a man believes in me, he does not believe in me only, but in the one who sent me."
John 12:44.

There are two ways to believe. The first way is to believe about God, meaning we believe that what is taught about God is really true. It's similar to believing that what is taught about devil or hell is true. This type of belief is more a statement of knowledge than an expression of faith.

The second way is to believe in God. This not only includes believing that what is taught God is true, but also includes trusting him and daring to be in relationship with him. It means believing without any doubt that he really is who he says he is, and he will do all he says he will do. I wouldn't believe any person to this same degree, no matter how highly others might praise him. It's easy to believe that someone is godly, but it's another matter to rely completely on him.

Those who believe in God believe everything written about God in Scripture. They dare to believe this in life and in death. This makes them true Christians and gives them everything they desire from God. A person with evil, hypocritical heart can't have this type of faith, forit'sa living faith, as described in the first commandment: "I am the Lord your God...You shall have no others gods" (Exodus 20:2-3).

Therefore, the little word in is well placed and should be carefully noted. We don't say, "I believe God the Father", or, "I believe about God the Father", but "I believe in God the Father, in Jesus Christ, in the Holy Spirit". Only God can give us this type of faith.