"Jesuit Theologian Karl Rahner said the future Christian will b a mystic or nothing at all."

Yes, in 1966, to be precise, Rahner predicted that "the devout Christian of the future will be a 'mystic'...or will cease to be anything at all." For Rahner, a genuine experience of God would be foundational for Christian life in a highly complex and global world. Rahner, however, (like the great Catholic mystics before him) never played down or divorced himself from a corporate encounter with the divine -- through liturgy, the sacraments, and in community/parish life with ordinary people. A corollary of the love of God was love of neighbor, love of those with whom we live and worship, whom mystics might be separated in degree, but not in kind. Thus it goes without saying, mystics and Rahner were very much at home worshipping in churches.