Stand therefore, having girded your waist with truth - Ephesians 6:14 NKJV
The comprehensive description of all the pieces of armour is a very useful aid in discerning and understanding them. The first piece of armour is our belt. A belt made of truth, holding up and keeping in place all the other pieces of armour. Naturally speaking, a belt is used to hold things in place; spiritually the belt of truth does the same thing. Truth keeps us secure in Christ and makes effective all the other pieces of armour.
What does truth mean here?
1 Corinthians 5:8 Therefore let us keep the feast, not with old leaven, nor with the leaven of malice and wickedness, but with the unleavened [bread] of sincerity and truth. (NKJV)
2 Corinthians 1:12 For our boasting is this: the testimony of our conscience that we conducted ourselves in the world in simplicity and godly sincerity, not with fleshly wisdom but by the grace of God, and more abundantly toward you. (NKJV)
Truth is the sincerity of the heart. Sincerity leads us to be open to God. It keeps our motives pure, devoid of malice and wickedness towards our fellow men. Are you seeking spiritual gifts as an aid to popularity or a means of serving God better? Keeping our hearts pure is essential if we are to be effective in spiritual warfare. This is the belt of truth.
The belt of truth involves truth in two places; in our hearts and in our minds.
In the heart
In the heart - 1 Corinthians 5:8 and 2 Corinthians 1:12 describes truth and how it relates to our hearts. This kind of truth should influence our whole attitude. Holding malice and bitterness against our fellow brothers and sisters in the faith puts a big dent in our armour. It also leaves us wide open to demonic attack. Our prayers of faith will be rendered ineffective if we do not wear the belt of truth. Truth is like a watch guard. It keeps us on the straight and narrow. Is your heart right before God?
Truth in our hearts means serving God with the right motives, and loving and serving our fellow brothers and sisters in Christ with sincerity.
In our minds
1 Peter 1:13-18 Therefore gird up the loins of your mind, be sober, and rest [your] hope fully upon the grace that is to be brought to you at the revelation of Jesus Christ; 14 as obedient children, not conforming yourselves to the former lusts, [as] in your ignorance; 15 but as He who called you [is] holy, you also be holy in all [your] conduct,
16 because it is written, "Be holy, for I am holy." 17 And if you call on the Father, who without partiality judges according to each one's work, conduct yourselves throughout the time of your stay [here] in fear; 18 knowing that you were not redeemed with corruptible things, [like] silver or gold, from your aimless conduct [received] by tradition from your fathers, (NKJV)
2 Timothy 2:15 Be diligent to present yourself approved to God, a worker who does not need to be ashamed, rightly dividing the word of truth. (NKJV)
Truth in the mind means having clarity of sound doctrine. What do you believe? Are you aware of what Christ has done for you? Does the mental knowledge of Christ victory on the cross translate into godly living in your life?
Truth in our heart makes us sincere and teachable before God. Truth in the mind helps to strengthen our wills to serve the Lord. These two, a sincere heart and a determined will combine to give us a firm girdle that keeps us rooted and grounded in Christ.
Truth in our hearts is sincerity. A heart devoid of sin towards God and bitterness towards man is a heart full of truth. Truth in the mind is exerting our will in serving the Lord. It is acting on what we know is true. Truth is not a mental perception of the truth but rather an embracing and living of the truth.
How to put on the belt of truth
Since the belt of truth involves our hearts and minds we have to make an adjustment in both these places to put it on. Make it a daily habit of checking your armour of truth. Are you right with the Lord? Is there any untruth lingering in your heart? Are you embracing known sin? What about your relationship with people? Any bitterness or malice being entertained?
Then make sure your mind is embracing sound doctrine. This will help to equip your will in serving the Lord. Below are seven helpful aids in embracing sound doctrine as given by one of the old-time teachers of the word - William Gurnall, a Puritan who lived in the 17th century in England. These points have been rewritten in modern day English.
The Christian in Complete Armour
(First Banner of truth reprinted 1964, ISBN 0851511961)