* the personal relationship with G'd in silent prayer is
nonverbal. G'd knows all things, is part of all things, it makes no sense to tell G'd anything. hence: *silent* prayer. It __does___ make sense to listen though , with your heart. And in the gentle *felt* presence your wounds may heal, and your love may grow. why *felt* presence? because G'd is everywhere, where else would G'd be. so you don't pray for G'ds presence. you pray to immerse into it.
* this immersion is not about fancy mystical experiences, but about healing in the presence of what as Christians we call G'd; it often is initially calm, then happy, ecstatic to some, and then that makes room for neither ecstasy nor void but pure presence, a state that can be experienced, but not described appropriately. On that path there lays and lurks inner work on your personal baggage, a liberating cleansing process, which is not only fun while it lasts, and a process which contemplative teachers today could call 'purifications'. The beatifications of the sermon on the mount give a fairly good step by step guidance of this purification process which leads to life "in Christo", as Paul describes it.
* contemplative or silent prayer was and is an outlier, yes, however certainly not in early Christianity, see the sibling comment for a random quick example
https://news.ycombinator.com/item?id=26497034
* contemplative / silent prayer, like comparable Jewish and Islamic traditions, and like a number of eastern traditions, puts the experiential personal liberation above authoritative teachings of some church or another. It's a radical shift of authority from rulebooks and logical learning to an inner process, guided and supported by open minded teachers.
* I respectfully doubt you have read the book. It is anything but superficial.
May I ask if you have personal experience with any kind of meditation, secular (like MBSR) or in some religious tradition?