The word testament and will mean the same thing. So, when we talk about the new testament or the new will of God, we’re talking about the same thing. A new covenant. A testament or a will, is a written document, which one provides for his estate. It’s always future tense. You’re saying “this is my will, my desire, my expectation.”
A testament or will implies that someone has something to will. Second, it implies death. When someone makes a will, one has their mind centered on after their departure, what do they want to happen with their possessions or who do they want them to go to.