Johan Adam Heyns is probably the most productive and noteworthy Afrikaans theologian of the twentieth century, born in South Africa. He was a real pioneer in his field. It is a well known fact that the kingdom of God played a vital role in all of his work. In fact, he used it as a systematic-theological category, which flows like a perennial river of opportunity, consistently through all of his writings. It gave him the opportunity to be consistent in both his systematic theology and in his ethics. Heyns used the kingdom of God as a systematic-theological category to show clearly how man and God can be co-workers in this world in a dialogical relationship. This relationship, of which God is the initiator, are characterised by the covenant between God, the Father-King, and man, the obedient child-servant. He also used the opportunity to integrate his love for philosophy with his love for theology. This integration opened up a wide spectrum of thoughts, ideas and meanings which he could scientifically analyze, explore, connect and merge together systematically. His contact with Stoker and their shared Calvinistic worldview as well as their shared Afrikaans culture and Christian religion, together with the influence of amongst others Du Toit and Snyman, Oberholzer, Vollenhoven, Barth, Brunner and Berkouwer, laid the foundation for his frame of reference. Unfortunately there was philosophical flooding from time to time, because it caused him to fill the kingdom of God with philosophical concepts which allowed him to think of the kingdom of God as an ontological cosmic-universal entity. His philosophical background and connection also leads to some inadequate speculations in his theology and especially in his eschatology. Inadmissibly he didn’t always use the Bible appropriately, although his doctrine of Scripture and hermeneutics were satisfactory. Heyns could have explored the important part which prayer must play in theology more thoroughly. But he did pioneer’s work in Dogmatics and Ethics in Afrikaans and as an ecumenist and church leader, which we must really appreciate. Lastly his philosophical modus operandi also had a positive side. It helped him to differentiate between important theological concepts. Heyns distinguished between the rule of God and the kingdom of God, as well as between the realisation of the kingdom of God and the eschatological fulfilment of God’s kingdom. These differentiations were tested on some theological problems, including the question whether the kingdom of God is really an ontological entity, the Theodicy problem and the “Nah-erwartung” problem. It was found that these differentiations, when used consistently, have valuable theological problem solving abilities. Although Heyns perhaps didn’t realise this, and he weren’t consistent in the use of these differentiations, he must be credited for identifying and clarifying them.