Grieve not the Holy Spirit of God (mh lupeite to pneuma to agion tou qeou). "Cease grieving" or "do not have the habit of grieving." Who of us has not sometimes grieved the Holy Spirit? In whom (en wi). Not "in which." Ye were sealed (espragisqhte). See Matthew 1:13 for this verb, and Matthew 1:14 for apolutrwsew, the day when final redemption is realized.