It is simply not true that all post-millennialists believe everyone will become a Christian before Christ returns. Even the assumptions within the statement are wrong. It in fact, completely misses the return in judgment against Israel, in which the martyred saints participated, within the timeframe that Jesus said it would occur. Furthermore, Jesus plainly said His kingdom was 1) spiritual and 2) would exist alongside those not in it. Be careful of buying hasty generalizations rhetorically used in attempts to discredit scripture-based hermeneutics.