A relational view of God’s sovereignty begins not with philosophical a prioris such as “God is by definition the being greater than which none can be conceived” or “If there’s one maverick molecule in the universe, God is not God” but with God as the personal, loving, self-involving, passionate, relational Yahweh of Israel and Father of Jesus Christ.
This God is not aloof or self-sufficient in himself or impassible. His deity, as Barth taught us, is no prison. And as Jürgen Moltmann has taught us, his death on the cross is not a contradiction of his deity but the most profound revelation of it. And that because this God is love.
Does this all mean that God needs us? Not at all. This God could have lived forever satisfied with the communal love shared between Father, Son and Holy Spirit, but he chose to become vulnerable in relation to the world he created out of the overflowing of that love. Is that just a metaphysical compliment unnecessarily paid to God or a truth necessary to the biblical story of God with us? I would argue it is the latter. A God who literally needs the world is a pathetic God hardly worthy of worship.
The key insight for a non-process relational view of God’s sovereignty is that God is sovereign over his sovereignty. The missio dei is God’s choice to involve himself intimately with the world so as to be affected by it. That choice is rooted in God’s love and desire for reciprocal love freely offered by his human creatures. None of this detracts in any way from God’s sovereignty because God is sovereign over his sovereignty. To say that God can’t be vulnerable, can’t limit himself, can’t restrain his power to make room for other powers, is, ironically, to deny God’s sovereignty.