In the larger scheme of things, it may not be significant that one person chooses to betray God. However, when tens of thousands of those in the millennium kingdom, and tens of millions of others in the eternal kingdom have betrayed, and continue to betray God, we cannot possibly expect that the kingdom we read about in the Scriptures will become manifest anytime soon.
Just as Nehemiah and the Israelites were charged with rebuilding the gates to Jerusalem when they returned home after the Babylonian exile, so we too must rebuild our wall of spiritual protection by cleansing the rebellion and the filth from our hearts, minds, and souls, rebellion and filth that makes us subject to illness and death. We do so by choosing every day to live by Godly principles, and by seeking the guidance of the indwelling Holy Spirit Of God on every issue of mild or major significance.
Choosing to be in God's kingdom is choosing to embark on the journey to eternity. Much cleansing and restoration must take place so that we leave behind our old selves (however righteous you thought yourself to be) and become a new and spotless creation of God, and of the indwelling Holy Spirit Of God.