Firstly (and negatively): Suffering is intricately entwined with human freedom of will.
A: Suffering is not part of the original created Order as described in Genesis 1-2. In these chapters it is clearly stated that human rebellion initiated suffering in the world. At the other end of the Bible (Revelation 21) it is stated that the end of the present age will end suffering. This cosmos was made by a God who defines Himself as “perfect love” (1 John 4:8), and initially He declared everything He’d created, to be “very good”. ( Genesis 1: 31)
B: The potential for suffering necessarily exists where there is true freedom to make meaningful choices: Wrong decisions lead to wrong consequences. Freedom to make meaningful choices must exist if Love is to be expressed and have meaning, because true love cannot be demanded of, or forced from, or pre-programmed into anything, and still be true love. This potential for negative consequences exists with the possibility of choice in the same way that the possibility of “darkness” exists in the same instant of time as “light” comes into being.
C: Wrong choices, made in freedom, will lead to real consequences, and at least some of these consequences will result in suffering.
D: According to the account in Genesis 1-3, Adam and Eve chose to disregard God’s ordained order for them in the perfect environment of the garden in which He had placed them, and about the care of which He instructed them, and over which He gave them complete authority. It was this wrong choice which introduced suffering into the world, first by breaking the life-giving and life-sustaining communion between the humans and their Creator/Father: The spiritual connection was lost. And secondly, by allowing a most powerful and malevolent enemy to gain control over the world, because their authority and power to rule their world proceeded directly from that spiritual communion and the resources it alone provided. Apart from the resources born of this union with their Creator, Adam and Eve had no strength by which they could resist the spiritual power of a fallen archangel.
[It is the common evangelical understanding, based in the study of the biblical records and the early church writings that followed, that Satan was once an exalted angel--Lucifer, “the light bearer”- in God’s Presence, and perhaps the most powerful created being ever to live, who became filled with personal pride, and who incited a rebellion against God, which resulted in his banishment from his high position and from the highest heaven: And as well, the banishment of a large number of other angels with him, for a significant number of angels joined his attempted coup. Lucifer became Satan (the “adversary” or the “opponent” whom we know as “the devil”). The disgraced and fallen angels became the spiritual beings we call “demons” or “evil spirits”, and even “gods”. Why Lucifer was permitted to approach Adam and Eve is another important question, which has a most satisfactory answer, but which is far more than I want to deal with just now: I will probably set about adding this topic to this section at a future date.]