With an abstract idea it is ...

With an abstract idea it is possible to enter into a relation of formal knowledge, to become enthusiastic about it, and perhaps even to put it into practice; but it can never be followed in personal obedience. Christianity without the living Christ is inevitably Christianity without discipleship, and Christianity without discipleship is always Christianity without Christ.
With an abstract idea it is possible to enter into a relation of formal knowledge, to become enthusiastic about it, and perhaps even to put it into practice; but it can never be followed in personal obedience. Christianity without the living Christ is inevitably Christianity without discipleship, and Christianity without discipleship is always Christianity without Christ.

Quotes from the same author

The first call which every Christian experiences is the call to abandon the attachments of this world.
Nothing can be more cruel than the leniency which abandons others to their sin. Nothing can be more compassionate than the severe reprimand which calls another Christian in one’s community back from the path of sin.
The essence of optimism is that it takes no account of the present, but it is a source of inspiration, of vitality and hope where others have resigned; it enables a man to hold his head high, to claim the future for himself and not to abandon it to his enemy.
Destruction of the embryo in the mother's womb is a violation of the right to live which God has bestowed upon this nascent life.
Whenever the Psalter is abandoned, an incomparable treasure is lost to the Christian church. With its recovery will come unexpected power.