“But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth:” (2 Thessalonians 2:13)
They were lacking in the second part of this statement. They received the spirit because the word of God is spirit but the key element of truth was lacking?
“O foolish Galatians, who hath bewitched you, that ye should not obey the truth” (Galatians 3:1)
“Of his own will begat he us with the word of truth, that we should be a kind of firstfruits of his creatures.” (James 1:18)
“Brethren, if any of you do err from the truth, and one convert him; Let him know, that he which converteth the sinner from the error of his way shall save a soul from death, and shall hide a multitude of sins.” (James 5:20)
I wouldn't necessarily read into Galatians 3 that were saved in the true sense of the word.