St. Tikhon of Zadonsk
Do not worship God with material things and superficially, but with a good conscience, fear, love, obedience, thanksgiving, prayer and faith. For God is Spirit, nonmaterial, and is therefore worshipped in nothing else but in spirit and in truth (Jn. 4:24).
Mention the name of God with all reverence, fear and devotion, and that only when and where we ought to mention it, because the name of God is holy and aweful, and those that mention it without reverence sin grievously. Render, then, all reverence to the name of God as to God Himself. You mention the name of an earthly king with respect; that is as it should be. How much more should we mention the name of God the Heavenly King, which is revered, beloved and sweet to angels and to the souls of the saints, with extreme reverence.
The name of God is rightly mentioned in prayer, in glorification, in thanksgiving, in praise, and spiritual songs and in conversations and discourse befitting of Christians. That is when the conversation is about the Holy Word of God, about the Law and the Gospel, about the advent of Christ into the world, about His life on earth, His suffering and death which He endured for our sake, about death, about the Judgement of Christ, about eternal torment and everlasting life, and so on.
Do not mention it in other conversations without extreme need, and if there is need to mention it, mention it with all caution and due reverence.
Guard against mentioning the name of God in lies and jests, lest God's judgement come upon you at that moment. "For our God is a consuming fire" (Heb. 12:29).
Without living faith and the fear of God it is impossible to live in a godly way. Living faith is inspired in the human heart by contemplation of the word of God and by the Holy Spirit. For this reason we should read and heed the word of God and pray that God Himself ignite the lamp of faith in our heart. The fear of God arises most often from contemplation of the omnipresence of God and His omniscience. God is in essence everywhere present; and wherever we may be, He is with us; and whatever we may do, say, think, and undertake, we do, say, think, and undertake all before His holy eyes. And He knows our deeds far better than we do ourselves. Think about this, O Christian, and heed it, and with God's help the fear of God will be born in you. The fear of God will guard you and correct you everywhere and in all things, and will turn you away from every evil deed, and confirm you in every good deed. Thus day by day you will become better.
Keep God, then, before your spiritual eyes and you will have the fear of God, imitating the Psalmist, "I beheld the Lord ever before me"(Ps. 15:8). But what you ought to do will be made clear to you in subsequent points. Take heed, then, and endeavor to comply with it.
While standing in church attend diligently to the reading and singing. This gives birth to compunction, true prayer, heartfelt singing and thanksgiving. Avoid, then, standing bodily in church while wandering outside the church in mind, and standing bodily before God while wandering about in spirit in worldly affairs, lest that saying be applied to you, "his people draweth nigh unto Me with their mouth, and honoureth Me with their lips; but their heart is far from Me" (Mt. 15:8). While standing bodily in church, then, stand with heart and spirit as you stand before God. When you look upon the icons of the saints, call to mind that One is the Creator that created them and you, and that His purpose was the same for them as it is for you, that is, to save both them and you. They are glorified, and before you lies the same glory, only imitate their lives and you shall be saved.
Prayer consists not only in standing and bowing before God in body, and in reading written prayers, but even without that it is possible to pray in mind and spirit at all times and in everyplace. You can do it while walking, sitting, reclining, among people, and in solitude. Raise up your mind and heart to God, and so beg mercy and help from Him. For God is everywhere and in every place, and the doors to Him are always open, and it is easy to approach Him, not as with man. And we can approach Him with faith and with our prayer everywhere and at all times, and in every need and circumstance. We can say to Him mentally at any time, "Lord, have mercy, Lord help!" and so on.
The Law of God
Love the Word of God, that is the Scriptures, handed down to us by the prophets and apostles, as God Himself. For the word of God is the word of God's mouth. If you love God, then without fail you will love the word of God also. For the word of God is God's epistle or letter to us unworthy ones, and is His supreme gift to us for the sake of our salvation. If you love the Sender, then also love the letter which is sent from Him to you. For the word of God is given by God to me, to you, and to everyone, so that everyone who desires to be saved may receive salvation through it.
You love it when an earthly king writes you a letter, and you read it with love and joy. How much more must we read the letter of the Heavenly King with love and joy.
The word of God was not given to you so that it should lay written only on paper, but so that we may use it spiritually, that we may be enlightened and guided in the true way and salvation, that our morals may be corrected, and that we may live according to its rule in this world, and that we may please God. If you wish, therefore, to be a true Christian, then without fail you must take care to live by its rule. For the word of God is a heavenly seed. It must, then, yield fruit in us after its kind, that is a holy and heavenly life, otherwise it will accuse us on the day of the fearful Judgement of Christ. Live, therefore, as the word of God teaches, and then correct yourself. Do not pry idly into the mysteries.
Of the mystery of the All-Holy Trinity, the Most-Holy Eucharist, and other such things that are not revealed to us in the holy word of God, do not inquire idly, lest you fall into the snare of the devil and be tangled in it, and not be able to escape from thence, and so perish. For that which requires faith alone transcends our reasoning, and it is very dangerous to pry into these things. Keep yourself, then, from prying into things which are above you. Believe in all things as the Holy Scriptures teach, and as the Holy Church believes and establishes in accordance with it.
from: Journey to Heaven Counsels On the Particular Duties of Every Christian Our Father Among the Saints, Tikhon of Zadonsk, Bishop of Voronezh and Elets Jordanville, NY: Holy Trinity Monastery, 2004.