In his goodness, Christ has already counted us as his [children], and therefore we should never grieve him by our evil actions ... that he may never become an angry father who disinherits his sons..." Rule of St. Benedict: Prologue 5-6
This is an interesting passage in the Rule because Benedict applies the image of a father to Christ to encourage his monks to obedience as well as gratitude for the good gifts we have been given. The Rule of St. Benedict is not the only Christian text wherein a father image is applied to Christ, but Benedict uses it in a way typical of him; it is intimate without being overly sentimental.
Young children of loving parents often desire to be like them, so for us to relate to Christ as "father" is to understand ourselves as sons and daughters who desire to be like Him, or to use more colloquial expressions: to be "chips off the old block" or "apples fallen not far from the tree"!
In the baptismal ritual when, after the baptized have been immersed in the holy font (or had the water poured over their head), and anointed with sacred chrism, the minister says for all to hear, "Behold, another Christ!" This is our "prime directive" as Christians, so to speak: to obey Christ by striving to imitate him, to do as he did. This is really what monastics mean by simplicity, or purity of heart.
To be simple in this sense is to live a life that is framed by a single ultimate intention: to please God our creator by imitating Christ in order to live up to who and what our Creator intended us to be! Monastic simplicity, or purity of heart, is not primarily about possessing less stuff, or having less clutter in our lives, but about centering our lives on a single, unifying principle: to be as Christ for others.
That is our life's overarching purpose and our primary vocation -- at least it ought to be for the serious Christian. St. Benedict insists that his monks make proper use "of the good gifts which are in us" (Prol. 6) for the sake of serving others out of love for Christ.
Purity of heart is a gift of the Holy Spirit. It is a power (or spiritual energy) by which we center our life on Christ as our unifying principle, so that we do what we do out of love for Christ, striving to understand our work and relationships in terms of service and love for others, especially the needy. Knowing that God's grace enables us to do the good we do, and to realize (or actualize) who God intends us to be, we give God the glory in a spirit of gratitude -- a simple heart is always grateful.
Our freedom from the fear and anxiety, and the violence and selfishness of a world turned in on itself, is found in Christ, Benedict writes. Benedict's monastic way is intended not as an end in itself, but as a means for cultivating communion with Christ, especially the Christ encountered in one another. Communion with others in Christ is the basis of authentic spiritual freedom -- freedom from sin, for Love; and ultimately, from death, for Life!