According to Ephesians 1:13-14 The Holy Spirit is a seal to Christians heart as a claim by God that we are His. 2 Corinthians 1:22. The Holy Spirit is a confirmation to us that we are truly God’s own and He resides in us. When we allow the Holy Spirit there is conformity to the will of God; we will choose the will of God over the will of our flesh because we have His seal in us. We will always want to dwell in His presence, either in prayer, meditation of his word, praising Him or even in the fellowship with the people of God. Remember the spirit is always willing but the flesh is weak. (Matthew 26:41)
Carrying the seal of God signifies we are His and His resemblance, so we are in His image, the personality of the Holy Spirit is Holiness, that is why I believe anyone who claims to have the Holy Spirit in them but is not holy, only deceives his or herself. A good tree will only produce good fruit and a corrupt tree can not bear good fruit (Matthew 7:15–20.)
We have this seal of God till the day of redemption, it is everlasting once we are saved (Ephesians 4:30).
I really do not believe that once you are saved then forever saved, you are only forever saved when you keep abiding in God, once you are outside His will and lust after the flesh, you will need to rededicate your life to Jesus again to be saved. The enemy knows this too and that is why he is after souls, especially once you are saved, you need to be more careful because that is when there is more temptation to face, but remember God is faithful, He will always provide a way of escape (1 Corinthians 10:13).
I hope you remain in Christ and if you are not yet in Him, please allow Him and you will have His seal (Holy Spirit) in you.
Prayer: Dear Jesus, help me to remain in you always and for the remaining days of my life, so that I will do your will and my life will keep bearing good fruit only.
Remain Blessed 🙂