For Francis, the fundamental name of God is "Good." Living sine proprio, without anything that is one's own, frees one to accept everything as God's good gift. The image of God from James, chapter 1, "the Father of lights, the giver of every good and perfect gift," is fundamental.
In the Praises to Be Said at All the Hours, Francis concludes as follows:
All powerful, most holy,
most high, and supreme God:
You Who alone are good,
may we give You
all praise, all glory,
all thanks, all honor,
and all good things,
So be it.
So be it.
Likewise, in the Praises of God, Francis says:
You are Three and One, Lord God of gods,
You are good, all good, the highest good,
Lord God, living and true.
And in the exhortation near the end of the later version of the Rule, he says:
ThereforeIt's hard not to see an echo of the words of Our Lord: "Why do you call me good? One is good. God alone."
let us desire nothing else
let us wish for nothing else
let nothing else please us
and cause us delight
except our Creator and Redeemer and Savior
the one true God,
Who is the Fullness of Good
all good, every good, the true and supreme good
Who alone is Good
merciful and gentle
delectable and sweet
Bonaventure's theology of the Trinity has been explored by Zachary Hayes, OFM, and others at great length. Fundamental to this is a reflection on the logic of God's goodness and love, which owes much to Denys (Pseudo-Dionysius) and Richard of St. Victor, as well as to a Franciscan vision of God's all pervasive goodness.
From Denys, Bonaventure derives a notion of the self-diffusive nature of good. God wants to spread God's goodness around. As in Richard, Bonaventure argues that perfect love is necessarily Trinitarian. Perfect love wants to share itself with an equal. Therefore the Father has a Son. Love is more perfect when two jointly share love for a third. Therefore the Father and Son jointly are the principle of a third divine and co-equal person, the Spirit. Bonaventure speaks of love (amor) that is purely gratuitous (the Father), purely owed (the Holy Spirit), and mixed (the Son). Both Son and Spirit receive all that they are ultimately from the Father, who is the fontal fullness of divinity and the fons et origo of the Trinity. The Son, moreover, receives from the Father that he is jointly the principle of the Spirit. This is an interesting middle position between Greek and Latin theologies of the Trinity. The filioque is affirmed but in a way reminscent of Thomas Aquinas attempt to reconcile the two. (Not that the Orthodox would necessarily be wholly pleased, but I think they could see the influence of the Greek fathers in this, as well as Augustine.)
But what is interesting about Bonaventure on the Trinity is the way in which the Word functions as exemplar, precisely in his total dependence, for all that he is, on the Father. As Hayes has observed, Franciscan poverty seems to be written into a Trinitarian ontology. The Second Person is ontologically poor, yet is eternally and consubstantially, the recipient of divine being and every good gift. When this central person of the Trinity becomes incarnate in the midst of history, he historicizes the eternal relationships among the persons of the Trinity, and invites us to reenter, in and through Jesus, our original poverty (in the garden). Francis himself taught that the image of God was Christ centered. For Bonaventure, the eternal exemplar is also historical in the person of Jesus of Nazareth. Returning to humility and poverty, reorients us to be the creatures God made us to be.
That brings me back to Richard and Denys. The Trinity may achieve the fullness of perfection when there are three. There is no necessary self-diffusion of good beyond that. But it is fitting that God should want to share God's life with another who is not equal. The purely gratuitous love of the Father, which necessarily expresses itself in Son and Spirit, also overflows to create the universe out of nothing, on the pattern eternally generated within the Son as image of the Father's fullness. Every creature reflects God's glory. And humankind in particular is the image and likeness of God.
There is a place for a consciousness of sin in all this. Faced with God's goodness, we can see how vile we often are. Hence the need to do penance. But the accent is on the joy of knowing God our Father in Christ our Lord and Brother by the grace of the Holy Spirit.
The notion of God the Father as fontal fullness, moreover, points us to a set of metaphors for the Trinitarian persons that helps complement the masculine images of Father, Son, and Spirit. Natural metaphors are one thing. Feminine metaphors are also required. But we ought not to think that we can do away with something so fundamental to Jesus as the notion of God as "Abba, Father."