How far can evil go in attacking God's creation?

The fact of Jesus Christ seems to imply a 'two phase' view of God's creation.

The first phase was the Heaven of our God (Father and Mother) among their spirit children. As unincarnated spirits, the children of God lacked the agency to become autonomous creators; they could not, therefore, participate in the ongoing work of creating.

Some of the children of God turned against the plan of loving creation, becoming the demons and being cast out. But these demons commenced their work against creation - subversion, destruction, inversion - which continues.

(Others of God's children opted-out of the whole thing - returning to non-consciousness.)

Phase two was to enable some of God's children (those who chose the path) to participate in creation, as fully as their capacities would allow. This was made possible by creating earth and mortal life - during which some who loved God and their fellow Men were able to make partial and temporary contributions to creation. But to enable this in fullness and completeness was the work of Jesus Christ.

After Jesus, mortal Men could make a commitment of love and follow Jesus through the portal death, resurrect into Heaven; and there live eternally and able to participate in creation.

By this means, God was able (open-endedly) to expand and enrich the loving and familial work of creation; and 'insulate' the process of on-going Heavenly creation from the corruption of demonic activity.

Thus the Heaven of Life Everlasting is unlimited is size and scope; and safe from evil.