“In Him” is the operative in this verse. “You also” is referring to a select individual who is “in Him,” Jesus the Christ of God by accepting Him as Lord and Savior.
A great deception prevalent in the world today is that a person can live like the devil and still be “In Him.” This is the message of the modernist, warm fuzzy, Gospel, so called, preachers of our times.
But those who have received and love Jesus and keep His commandments, according to the Word of God, are those who are actually “In Him.” If you are one of these disciples then you are “sealed with the promised Holy Spirit.”
If, indeed, you are sealed with the Holy Spirit then you should eagerly embrace His Presence, power, and give Him prominence in your life. His prominence should be in evidence in all that you say and do.
You should be living a Holy life, speaking in tongues, and manifesting the fruit and gifts of the Holy Spirit of promise if, in truth, you are “In Him.”