Polycarp exhorts the Philippian church to serve the Lord in fear and truth.
" 'Wherefore, girding up your loins,' 'serve the Lord in fear' and truth, as those who have forsaken the vain, empty talk and error of the multitude, and 'believed in Him who raised up our Lord Jesus Christ from the dead, and gave Him glory,' and a throne at His right hand." (Polycarp 2)Notice that God does not call those who are already perfect, but He calls those whom He may make to be perfect. The Philippians were not called because they were already serving God, but now that they have been called, Polycarp exhorts them to serve God. The "Wherefore" is on account of the Joy they have received from knowing the invisible God. Now that they have received this Joy, the should turn their attention to serving the one who has given then that joy; the one whom they have come to know and to love. In serving God, fear or reverence is not enough, we must also serve in truth; we must serve Him from a true and whole heart, not feigning service, but serving from the heart.
Polycarp also reminds them of the reward for those who serve God well.
"But He who raised Him up from the dead will raise up us also, if we do His will, and walk in His commandments, and love what He loved, keeping ourselves from all unrighteousness, covetousness, love of money, evil speaking, false witness; 'not rendering evil for evil, or railing for railing,' or blow for blow, or cursing for cursing, but being mindful of what the Lord said in His teaching: 'Judge not, that ye be not judged; forgive, and it shall be forgiven unto you; be merciful, that ye may obtain mercy; with what measure ye mete, it shall be measured to you again;' and once more, 'Blessed are the poor, and those that are persecuted for righteousness’ sake, for theirs is the kingdom of God.' " (Polycarp 2)While our service to God may abound in earthly blessings, our true reward is a heavenly blessing; an eternal blessing rather than a temporal blessing; our true reward is life everlasting with Him where He is.
Some think of Christianity as "fire insurance" allowing then to continue to lives their life as they choose knowing that, in the end, they have their "ticket punched" for heaven. However, Polycarp did not understand Christianity in this way. To him, Christianity was a life long journey of learning to become more and more like Him. One day our journey would end when we take up our residency with Him in heaven, but until then, our lives should be spent knowing, conforming, and growing fruit for Christ. For those who such occupy their lives, heaven is an eventual certainty.