My observation has been that it is possible for people who have believed the gospel and received salvation, are also able to learn, without coming to the knowledge of the truth.
God wants us to move on in our understanding and He wants us to mature in our knowledge and wisdom. However, a person who has a mind to learn but does not have a mind to trust and obey will never mature or grow. They will be mislead.
We must grasp the basics of Biblical truth and salvation, and then move on to maturity. One of the snares for the more intellectually gifted and astute is that they become proud of their knowledge, not realizing that their accomplishments are carnal, even though they are related to spiritual concepts. Spiritual pride is the worst of all types of pride.
It is faith and obedience that opens our eyes to God's revealed truth. If our knowledge, understanding and wisdom does not produce godliness then it is producing confusion. Jesus did not die and rise again to make us "smart" but to make us holy.
The first lie is the same lie today. Sin will not separate you from God.