St. Hilarion Troitsky, New Martyr of Russia and righteous Confessor of the Church, brilliantly sets for the Scriptural and Patristic understanding of what Christ came to establish: not an invisible, personal “Christianity” but the Church which He promised He would build (cf. Matt 16:18). The question posed as the title of the work must be asked and answered by everyone who calls themselves a Christian. St. Hilarion is our guide if we are unsure how to answer.   

Read the text of "Christianity or the Church" here: http://orthodoxinfo.com/inquirers/sthilarion_church.aspx  

2:47 The Church was designed to reflect the perfect unity of the Three-One God 

4:47 There is no form of unity on earth that compares to the unity of the Church 

7:17 St. Cyprian and St. Cyril of Alexandria on the unity of the Church 

9:02 Christ did not come simply to teach, but to build his Church (cf. Matt 16:18) 

10:40 On the Tower of Babel and the inadequacy of human law to rid us of egoism, the obstacle of Church unity 

14:05 Church unity is organic, like a tree and its branches 

14:22 St. Paul on the physical and organic nature of Church unity 

16:19 How is such a unity possible? 

16:46 The command to love is not enough, we must have the power, and we have this in the Church 

17:43 The Holy Spirit is the source of life and organic Church unity 

18:40 What is the unity of the Spirit? St. John Chrysostom, Blessed Theodoret, Blessed Jerome, and Blessed Theopylact answer 

20:08 According to the teaching of the Apostle, all Church life is a manifestation of God's Holy Spirit 

20:58 God is love and acts in love in His Church 

21:31 The teachings of St. Paul on the Church and on love are inseparably linked, despite what some scholars say 

22:50 All of [St. Paul’s] Christian ethics are based upon the dogmatic teaching about the Church.  

23:31 Christ creates not only a moral person, but a perfect society, i.e. the Church 

24:05 “Outside the Church and without the Church, Christian life is impossible.” 

25:14 On Eph 4:16: “the body of the Church reaches perfection in all its members” 

27:07 “the perfection of the human personality depends upon its belonging to the Church as a living organism” 

27:46 A hand cut from the body, a branch cut from a tree, a ray separated from the sun 

29:29 “Spiritual life can exist only in an organic unity with the Universal Church” 

30:04 “Dogmatic truths have moral significance, and Christian morals are founded on dogma.” 

31:18 The word "Church" (ekklisia) appears 110 times in the NT, while "Christianity" is completely unknown 

32:05 What did it mean to be a Christian in the early days of the Church? 

32:57 How St. Paul joined the Church 

33:59 Saul (St. Paul) did not persecute followers of some Christian teaching, but the Church  

35:29 The Church is not a theory but life itself 

35:57 The Church is not a school but a life 

36:35 Protestant teaching of an “invisible” church 

37:53 We will look at two Church fathers who dealt extensively with the dogma of the Church: St. Cyprian and St. Augustine

"Outside the Church and without the Church, Christian life is impossible. Without the Church, the Christian teaching alone remains as an empty sound, for Christian life is Church life. Only in the life of the Church can a person live and develop. In a bodily organism, separate members never grow or develop independently of one another, but always and only in connection with the whole organism. The same applies to the Church. For the growth of the Church is at the same time the growth of its members." -St. Hilarion