The Father, the Son, and the Holy Spirit has a perfect coincidence of will and purpose. They have a covenant of redemption in which they made promises to one another, and in which their different tasks in salvation is distinguished but not separated. This article specifically also looks at the role of the Holy Spirit in the covenant of redemption.
This article features some of the major characteristics of the decree of God, with ample biblical support.
The death of Christ was not accidental. Rather, it was a definite and certain event determined by God in his eternal purpose. The author of this article explains this assertion in detail from Scripture.