Here is the difference. Believing is an “is”— much like arithmetic or true science. We don’t struggle with the possibility that there is some other explanation for 2 + 2 = 4, for example. Or that when we plant tomatoes, we get tomatoes.
It doesn’t keep us, or the neighbors, awake. We all believe in those universal truths. When you think of it, we carry out the act of believing a thousand times a day. We don’t check the legs of chairs before we sit down. We don’t check under the hood every time we start our car.
Faith = Pistis in the Greek Believing = Pisteuo in the Greek.
“But Abram said, ‘Lord God, what will You give me, seeing I go childless, and the heir of my house is Eliezer of Damascus?’ Then Abram said, ‘Look, You have given me no offspring; indeed one born in my house is my heir!’
“And behold, the word of the Lord came to him, saying, ‘This one shall not be your heir, but one who will come from your own body shall be your heir.’ Then He brought him outside and said, ‘Look now toward heaven, and count the stars if you are able to number them.’ And He said to him, ‘So shall your descendants be.’
“And he believed in the Lord, and He accounted it to him for righteousness” (Genesis 15:1-6, NKJV).
Righteousness can be defined as the God-given ability to stand before God without any sense of sin, guilt, or condemnation.
He was convinced beyond any doubt.
As above, we already know how to believe many things in our daily lives beyond any doubt.
“Fully persuaded,” to me, is the very best definition of believing. There is no room for anything else. It is an “is.”