Is certainty the opposite of faith? Does certainty rule out faith? Can a Christian be faithful to God without being certain?

Certainty is the firm, settled belief in the truthfulness of something. The object of certainty is the certitude that something that is believed is unassailable, that is, there is an absence of any objective proof to the contrary.

Certainty in the cardinal doctrines of the Christian faith is based on the certitude that God is (Heb. 11:6; Ps. 19:1-2), and that He has spoken (Heb. 1:1; Deut. 18:18-20; Jer. 1:9), and that what He has said is unassailable or incontrovertible truth (Heb. 6:18; Tit. 1:2). The Scriptures are the written record of God’s special revelation (Exod. 31:18; Jer. 30:2; I Cor. 14:37; 2 Tim. 3:16; 2 Pet. 3:16). While a Christian may doubt, yet he has no reason to doubt because of the certitude of God’s revelation. In fact, it is impossible to please God without faith in Him (Heb. 11:6). Faith is not the opposite of certainty, for faith in God’s revelation provides us with two things: the assurance of things for which we hope from God’s Word, and the certain conviction of the unseen things revealed in God’s Word (Heb. 11:1).

The absence of such certitude makes it impossible for a Christian to know to what he is to be faithful? How can one be faithful to the truth if there is uncertainty or doubt as to what is truth? How can one be a disciple of Christ in the fullest sense unless certainty in God’s revelation is possible? Certainty means that God’s Word is objective, propositional revelation and that it can be known (John 8:31-32; 16:13; 17:8; I John 2:20-21). God’s will is that we know the truth because truth can be known. While we can know only that which God reveals, for God alone is omniscient, yet God desires that we know the truth to the extent that He has revealed it in the Scriptures so that we can be faithful to Him.

The alternative to faithfulness to the Lord based on certainty is that we can only know with a great deal of assurance or confidence, short of certainty, which enables us to function as Christ’s followers, but always with a sense of doubt or uncertainty regarding our beliefs. We are able to get by as it were. The mind set that we cannot be certain results in "ever learning, and never able to come to the knowledge of the truth"(2 Tim. 3:7).

Doubt, as a normal condition of frailty and fallenness, may fall into the category of unbelief when it is applied to the truthfulness of God and His Word. We may doubt "how" God will accomplish that which He has promised, or we may doubt "when" God will accomplish His promises (note the yet to be fulfilled promises in Heb. 11:13-16}. But to doubt that God has promised and will do what He promises is unbelief. Unbelief is then a culpable act of disbelief in the faithfulness of God. Even to doubt that when God speaks we cannot know is, in effect, disbelief in the work of God through the Spirit of making His word and His will known (I Cor. 2:6-16; I John 2:25-27).

God has provided us with a certified hope by which we can be followers of His living by faith and in the certainty of the inviolable truths of His Word (Heb. 6:18-19).