When Christ's millennial reign commences, the priests in the kingdom of God will become a privileged group. They will have fought the good fight and finished the race and will hear the words "Well done, good and faithful servant." When the seventh trumpet is finally blown, they will have earned eternal life. They will be the first human beings to have earned eternal life, and more importantly, they will be in the earth yet not subject to its rules. They will reign with Christ for one thousand years.
These priests of God will have the difficult job of convincing the people of the world that they should forego sin and depravity in favor of living in accordance with spiritual principles. Many will continue in sin and depravity, but many others will repent and will return to God. For those who repent and choose to accept the indwelling Holy Spirit of God, if they remain faithful to the end, they will have earned a place in the final Kingdom of God at the end of time, but will have missed their opportunity to be members of the millennial kingdom of Christ. Unlike those in the millennial kingdom, these individuals will continue to be subject to sin, illness and death for the first portion of the millennial reign. Thereafter, as righteousness increases, health and longevity also will begin to increase, and living for one hundred years or more will become commonplace.
Clearly, while it is true that we are saved by grace from having hell as our certain destination, and anyone who genuinely desires God's protection can have the indwelling Holy Spirit, the pearl of great price is a ticket into the millennial kingdom of God. This ticket must be earned through radical obedience to spiritual principles. It is for this reason that Jesus admonished his disciples to avoid even thinking of sin. They were taught to take every thought captive and make it obedient to Christ's teachings because transformation comes only from a renewing of the mind.
Wanting to be part of God's kingdom and doing everything necessary to be part of it are very different. For those who genuinely desire to be part of God's kingdom, they must adhere to spiritual principles in their thoughts, words and actions. They also must complete the mission and purpose for which they came to the earth. It may seem impossible to achieve this latter goal, but with God nothing is impossible.