The Unified Spiritual Kingdom
According to the provided sources, the terms "Kingdom of God" and "Kingdom of Heaven" in doctrinal teachings are used as a single concept. This is confirmed, for example, by the material from file link txt (page 433), which states: "First of all, let us turn to the very term 'Kingdom of Heaven' or 'Kingdom of God'. Both terms undoubtedly have the same meaning, since in the language of that time people constantly said 'heaven' instead of 'God'..."Additional confirmation of their synonymy is found in the information from file link txt, where it is noted that the Evangelist Matthew uses the expression "Kingdom of Heaven" in nearly 32 instances and "Kingdom of God" in 5. A comparison of the parallel passages convinces that these expressions are synonymous.Regarding how, where, and when this Kingdom manifests, the teaching emphasizes several aspects:1. The Kingdom is not a visible, external possession or territory but principally an internal, spiritual reality. This is confirmed by a statement from file link txt: "Only true confessors of the Lord are given to understand that the Kingdom of God will come not in a noticeable manner, for it is within us (Luke 17:21)." Thus, the Kingdom manifests in the life of the believer, in their heart, and consequently in the community of the Church.2. The teaching also considers the Kingdom as having both an eschatological (i.e., future) and present dimension. In one of the sources ( link txt) it is asserted that: "The Kingdom of Heaven will come regardless of people’s desires or prayers... Christ referred to the earthly realm as the Kingdom of God, the assembly of all those who act according to God's will..." Here, it is emphasized that the spiritual Kingdom is already being realized in the way people fulfill God's will in everyday life.3. Another aspect is that the Kingdom manifests itself through the conciliarity of the Church. In file link txt it is noted: "The words of Scripture 'Kingdom of God' denote the One, Holy, Conciliar, and Apostolic Church created by the Lord. This Church is called the Kingdom of Heaven..." Thus, the fellowship of all true confessors evidences the emergence of the Kingdom within the body of the Church founded by Christ.In summary, doctrinal teachings present the Kingdom of God (or, synonymously, the Kingdom of Heaven) not only as an eschatological hope for the future but also as a reality manifesting here and now. It is revealed in the spiritual transformation of the individual, in a life imbued with God's will, and in the conciliar unity of the Church, wherein divine rule is present.Supporting citation(s): "First of all, let us turn to the very term 'Kingdom of Heaven' or 'Kingdom of God'. Both terms undoubtedly have the same meaning, since in the language of that time people constantly said 'heaven' instead of 'God'..." (source: link txt, page: 433) "The comparison of the parallel passages convinces that these expressions are synonymous." (source: link txt) "Only true confessors of the Lord are given to understand that the Kingdom of God will come not in a noticeable manner, for it is within us (Luke 17:21)." (source: link txt) "The words of Scripture 'Kingdom of God'... denote the One, Holy, Conciliar, and Apostolic Church created by the Lord. This Church is called the Kingdom of Heaven..." (source: link txt)These sources clearly indicate that both names refer to the same spiritual Kingdom, which manifests within the individual and in the unity of the true believers of the Church, being both a present reality and a future hope.