Grieve not the Holy Spirit of God (mē lupeite to pneuma to hagion tou theou). “Cease grieving” or “do not have the habit of grieving.” Who of us has not sometimes grieved the Holy Spirit?
In whom (en hōi). Not “in which.”
Ye were sealed (esphragisthēte). See note on Eph 1:13 for this verb, and Eph 1:14 for apolutrōseōs, the day when final redemption is realized.