This is the definition of faith that I grew up with.*
Saving faith consists of three things. Firstly there must be knowledge of the truth; secondly there must be assent or consent to the truth; and thirdly there must be an actual entrusting of ourselves to the person revealed in the truth.
When it’s put in this way, it should be clear that the gospel message is fundamentally concerned with presenting sinners with a Saviour. Glad tidings of great joy: a Saviour, Christ the Lord. This person – the person of the Saviour – is what’s offered to us as what we should believe in. And it is important that those who hear this message are assured that Christ is both a suitable and a sufficient Saviour for them – that is, that each hearer of the gospel message should treat this revelation as if it was meant for them and nobody else, and believe it.
But: what’s meant by believing it is not merely that people should consent that the gospel is a good message to hear and agree that the doctrines are true and make sense. Rather, in addition to coming round to consent to the truth of the message, faith must also include this further ingredient which reaches, through the message, to the person of the Saviour himself, and that is the element which I have been calling all along in the current discussion by the name of trust.
Of course, if people get as far as consenting to the truth, that has to be acknowledged as a great mercy, as far as it goes (because too many people don’t agree or consent to anything like it) – and people are, actually, required to assent to the goodness and the truth of the gospel – you cannot be saved without assenting to the truths which scripture reveals, and dissent and rejection are undoubtedly one of the most fundamental manifestations of rebellion and disobedience to the authority of God and his word.
But still, a person can know all this truth and agree with it (and admire it and argue for it and not repudiate one strand of any teaching of scripture) – and still not go the further crucial step and actually entrust themselves to the person who the gospel reveals, taking him to be to them exactly the Saviour he is revealed to be to his people in the truth.
Therefore, while it must be confessed that the gospel message is doctrinal, and propositional, and demands to be acknowledged as true – that it is God’s authoritative truth which must be accepted and obeyed – yet, simultaneously it must be recognised that what the message is about is a person, a Saviour, Christ the Lord. The content of the propositions are always about Christ – as he said himself, ‘The scriptures testify of me.’
The testimony of scripture is a presentation of the Saviour from no end of beautiful angles – as friend, brother, teacher, pioneer, healer – metaphorically as the bread of life for hungry souls, the water of life for thirsty souls, the door to life for dead souls – in his mediatorial offices as prophet, priest, and king of his people. And in each of these ways, he is presented as the one who we must believe on, first and foremost: it is Christ himself who is the object of faith, rather than doctrines about him.
It’s one thing, for example, to know or be acquainted with the fact that Jesus said, ‘I am the good shepherd …’ it’s another and better thing to concur that Jesus is the good shepherd; but it’s another thing, better still, and crucial to saving faith, to receive and rest on Jesus to be your shepherd. Or to put it this way – while it’s one thing to know that his blood cleanses sinners from all sin, the crucial thing is to go to him for the cleansing that only his blood can provide.
To speak more particularly to the controversy at hand: receiving and resting on him, and going (or coming) to him, are more or less equivalent ways of saying trusting in him, and they constitute, or reflect, that aspect of saving faith which is fundamentally not something that can be done merely with the mind or intellect or understanding. This involves both more than the truth and more than the intellect: although faith necessarily (i) is grounded on the truth and (ii) includes the participation of the understanding, it does not qualify as saving faith unless it also includes (i) a union with Christ who is revealed in the truth, which can be described as (ii) a reliance on him with the whole soul – mind, and will, and emotions, and all.
This is the principal reason why mere knowledge isn’t good enough. Although you do need to know about him, your acquaintance with the doctrines does not answer the purpose of the gospel in presenting him for our acceptance. Food sitting on the table does me no good if I don’t reach out and eat it – and nor (speaking reverently) does all the goodness of God save my soul if I don’t taste for myself and see that he is good. The tasting, the eating and drinking, the cleansing and healing all need to be experienced by my soul, but all these things are provided in Christ, by Christ, on the basis of what Christ has done – they are all out of my reach if I don’t have him, and I must make contact with him by faith, if I am to have any benefit from these things which are the salvation he provides.
* Some day maybe I will tell you how I grew up with lots of definitions of lots of things and knew the bible and catechism inside out, and had the entire scheme of redemption worked out perfectly in my head – and how this suited me fine, until I started to realise that if this body of knowledge carried on staying in my head, I would still be lost unless it would also take possession of my heart. It’s those crucial eighteen inches, as a man who was much taller than me said – if the truth doesn’t travel down from your head into your heart, you’ve missed its whole point. These things are written so that you would believe that Jesus is the Christ, the Son of God, and that believing you would have life through his name. John 20:31.