1. understood without being openly expressed; implied (Dictionary.com)
2. unquestioning or unreserved; absolute (Dictionary.com)
Tacit faith: a faith that understands truths without being able to express all of it and their implications
Implicit faith: a faith that trusts unquestioningly in whatever is being taught (by the church)
... it must be confessed, that in the present dark state of our minds, even the most illuminated are ignorant of a great many things; and that many things are believed with an implicit [tacit] faith, especially by young beginners and babes in Christ, so far as they admit, in general, the whole scriptures to be the infallible standard of what is to be believed; in which are contained many things which they do not understand, and in as far as they embrace the leading doctrines of Christianity, in which many other truths concenter, which are thence deduced by evident consequence, and which they believe in their foundation or principle, as John writes concerning believers, that they knew all things, 1 John ii. 20. ...
[Herman Witsius, The Economy of the Covenants between God and Man – Comprehending A Complete Body of Divinity. (trans. William Crookshank; Original printed 1822; Reprinted Kingsburg, CA: den Dulk Christian Foundation, 1990; Distributed Phillipsburg, NJ: P&R Publishing), III.7.9. - Vol. 1, 376]
.. they [the Roman Catholic scholars] have invented the fiction of implicit faith, with which name decking the grossest ignorance, they delude the wretched populace to their great destruction. Nay, to state the fact more truly and plainly, this fiction not only buries true faith, but entirely destroys it. Is it faith to understand nothing, and merely submit your convictions implicitly to the Church? Faith consists not in ignorance, but in knowledge – knowledge not of God merely, but of the divine will. We do not obtain salvation either because we are prepared to embrace every dictate of the Church as true, or leave to the Church the province of inquiring and determining; but when we recognize God as a propitious Father through the reconciliation made by Christ, and Christ as given to us for righteousness, sanctification, and life. ...
[John Calvin, Institutes of the Christian Religion (trans. by Henry Beveridge; Grand Rapids, MI: Eerdmans, 1989), 3.2.2]
While we should certainly not be doctrinal minimalists, especially since growth in Christ would correlate with growth in knowledge of His truth, yet it is just as much certain that Christians are not born [again] mature in faith and knowledge. In fact, since God is infinite and we are not, we can never perfectly know Him. We think God's thoughts after Him, yet never exhausting God's truths even throughout eternity.
Knowledge of the Gospel is required for salvation, yet how much exactly of this knowledge must we have? Are the 4 spiritual laws sufficient? Maybe the "Roman Road", or the "2 ways to live" booklet have nailed the Gospel down to its bare essentials? Or maybe we can just reduce the Gospel to "God loves you", since after all simple village folks in 3rd world countries do not have the mental capacity to grasp abstract concepts?
In pre-Reformation times, the developing Roman church was just as adamant of the general stupidity of the populace and the concept of "implicit faith" was invented. Given the perceived stupidity of the laity, the Roman church had decided that faith in the Church was all that was necessary and the laity did not need to pay too much heed to Scripture. The Church became the mediator between Christ and the laity, dispensing grace to the faithful and nurturing them throughout life.
When the Reformation broke out, one of the Romish teachings that was attacked was this idea of implicit faith. Calvin in his Institutes attacked it viciously as a fiction which destroys true faith, "delud[ing] the wretched populace to their great destruction". Rather than making faith 'simpler', such 'faith' was no faith at all. It is not alright to merely believe in the church, but faith must have God as its object. Incidentally, this shows the emphasis on individual salvation is foundational to Protestantism, but I digress.
So faith must consist in knowing God and the Gospel, yet we are still no clearer to the answer to our query. How much knowledge is required for salvation? If one were to think that such is a mere academic exercise, consider this: Can one reject inerrancy and still be a Christian? Can one reject the humanity of Christ (Docetism) and still be a Christian? Can one reject the doctrines of grace (aka Calvinism) and be a Christian? Certainly, a Christian can be premillennial, postmillennial or amillennial in eschatology, but how about differences on other doctrines?
Such a question is furthermore not a way whereby we take on the prerogatives of God and decide who is saved and who is not saved. Rather, such is necessary in order to obey Scripture on evangelism, church discipline, and fellowship. If we do not know that a person who is unsaved is not actually saved, how can we seek them out to evangelize them? If we cannot recognize a false believer from a true one, how can we obey Titus 1:11 and Acts 20:28-31? And if we cannot discern the true from the false to some extent, how do we obey 2 Cor. 6:14-18?
A century or so after John Calvin, the Dutch pastor and theologian Herman Witsius wrote his magnum opus The Economy of the Covenants between God and Man. In his section on faith (III.7), the phrase "implicit faith" strangely crops up again, this time in a positive light. Yet reading the entirety of the section in context soon resolves this apparent contradiction between John Calvin and Herman Witsius. Having dispensed with the darkness of Romanist ex opere operato fideism, Witsius lived in a more peaceful time compared to the exigencies during the Reformation. The quetion of the basic truths that a Christian ought to embrace come to the fore.
In his Economy of the Covenants therefore, Witsius uses the term "implicit faith" to describe the faith young believers have. Such a faith is one which wholly rests upon Christ despite the little actual knowledge they currently have. Witsius then states the three fundamental doctrines which all Christian must believe in as 1) The divinity of the Scripture, 2) the message of the Gospel, 3) the divinity of Christ and the Godhead (III.7.10), with the understanding of course that such doctrines are to be understood as how the Scripture teach them to be.
Since there would be a clash in terminology between Calvin and Witsius, I have opted to use the term "tacit faith" to describe the Witsian idea of "implicit faith", based upon the dictionary definition of the word "tacit" as being a good fit for the concept. Baby Christians (not necessarily Christian babies or children) know little truth. Yet if we are to do justice to Scripture as quoted by Witsius in 1 Jn. 2:20, then we must insist that ALL who are Christians know the truth, even baby Christians.
The concept of tacit faith is thus a helpful aid to resolve this conundrum. All Christians have tacit faith, which is like faith and knowledge in seed form (cf Faith like a mustard seed — Lk. 17:6 cf Mk. 4:30-32). Believers would therefore naturally grow in faith and knowledge just like a seed naturally grows into a tree. If a professed Christian "grows" into error despite correction, then it is certain that the seed of faith and knowledge; the seed of regeneration, was never there in the first place.
Applied to the issue of doctrines, new believers need to know about Scripture, the Gospel and God. Yet because their faith is tacit, this means that their knowledge would conform to the orthodox understanding of all these despite being shallow versions of them. There would however be no baby Christians, in fact no Christians at all, who will hold to heretical views on any of these three points. While baby Christians do not understand what is homoousis and homoiousis, they would not hold to the Aryan position once they understand what it actually teaches. Similarly, no Christian would willingly embrace Pelagianism or Semi-Pelagianism (being denials of the Gospel), and no Christian would knowingly attack the inerrancy of Scripture and embrace Neo-Orthodoxy. Scripture, Gospel and God — embraced in the five solas, remain the definitive line diving Christianity from all false religions. Neo-Orthodoxy deny Sola Scriptura, Pelagianism and Semi-Pelagianism deny Sola Gratia Sola Fide, while Aryanism/ Jehovah Witnesses deny Solus Christus.
One consequent of this teaching is that there are probably more saved laity than saved clergy in heaven since the clergy "have educated themselves into perdition". It is thus possible for laity in Word-faith churches to be saved while their pastors are not. Not only is theological education fraught with inherent difficulties, it may even be the means by which professing believers enter perdition especially if they enter a liberal or neo-orthodox seminary, otherwise nicknamed "cemetery". [HT: Joel Tay]
It is therefore submitted that this idea of tacit faith (as opposed to implicit faith) is a useful Witsian concept to enable us to understand how faith and knowledge relate to salvation. Tacit faith is biblical, while implicit faith is not. The seed of faith (regeneration) within us germinates and brings forth good fruit of which growth in knowledge of God is one.