Looking at the context of Jesus' words, we see that the temporal things were important to people. The people wanted food, shelter, clothing, those things Jesus calls 'additions' or non-essentials which are provided AFTER we search for His Kingdom. How do we get there? First is a recognition of the value of His Kingdom over the value of temporal things. The righteousness of God is infinitely more valuable than what we think we need every day, a good meal, a comfortable bed or even safety! What we can't comprehend is the eternal nature of the Kingdom of God. It does not consist of food, money or even power. It is a relationship based first on God's eternal, everlasting, profound love for us and then on our response to that love (a reciprocation, a reflection of God's love). This may be the essence of God's Kingdom.
The Kingdom is not defined by rules or standards, it is defined by a relationship. This goes completely against the normal flow and understanding in our society. Jesus puts it most clearly in the form of parables. In the parable of the workers in the field, the owner hires workers at different hours of the day. Each worker contributes different levels of effort and time but they are all paid the same. So the twist here is a new set of values: all of them agreed to work, all of them came to work, all of them completed the work they were contracted to do, all of them had a relationship with the owner of the field, so they all receive the same wage, a relationship to the owner of the field and a new understanding of how to live. The generous monetary payment is just extra, an addition to what is really necessary.
So what does it mean for me to be a member of the Kingdom of God? Certainly it requires no social status, no position of power or responsibility, no amount of wealth. It is not even following a set of rules or being a member of a group of people or a religious organization. So what is it? Jesus says, "If my kingdom were of this world...". So is there any overlap between the eternal and spiritual nature of God's Kingdom and our earthly existence? It appears that the connection exists in the direction our life takes. This brings us back to "seek ye first", a value that consumes my heart and mind and that carries over into every other area of my existence. I must desire God's Kingdom to the extent that it impacts my choice of a wife, my choice in entertainment, my choice of education and work, my choice of words, even my choice of thoughts. This seems like an impossible task, which in our fallen state it is! But the journey toward God's Kingdom begins at the cross of Jesus.
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Which road leads to significance and value? In a careful study of history and humanity, it seems to be the road leading to the cross of Jesus Christ. The cross is the center of human history, the focus of the eternal time-continuum and the point of decision in every individual life. This is the great "crossroads" of life, taking the path toward God's Kingdom or away from God's Kingdom. I must come to a place of surrender, recognizing that my life has little significance in the scope of eternity unless I surrender my will, my hopes, my loves, my values to the purposes of the eternal God, the Creator and Sustainer of both the spiritual and the physical universe. I lose everything of true value in turning away from the cross of Jesus or I recognize the only thing of real value in surrender to Christ and the Kingdom of God at the cross.