Just a lack of understanding what they read. If a letter was written to the Corinthians, addressing their issues of their day, it wasn't written to us as is clear by the salutation. So, one must simply recognize that first, and then look at what was being said to THEM, and then determine how and if it has any direct applicability to us, or indirect applicability. Just slow, careful, reading followed by an understanding of how they may be applied to us today. The issues of the early church and near term remedies God set in motion back then were for the most part much different then those issues of the present day as well as how God deals with them and us today. This is why there us so much confusion on topics such as spiritual gifts or manifestations of the spirit. They were needed then and instituted for that period accordingly, but not now. Also, in the aforementioned example of letters to the Corinthians, it addressed THEIR specific, CONGREGATIONAL issues, yet people today read the Corinthian letters as though the were written to us today as a church universally. Did the Corinthians have different issues than the Ephesians? Probably. Did the Ephesians have different issues than the Galatians? Probably. And just look at the 7 churches of Asia in Revelation. Some good some bad, some on track and some not so much. So the letters once again, WEREN'T addressed to us, and for sure not to us today universally as one giant, global church, but they are compiled for our learning, as some of us may have similar issues severally as individuals, or congregationaly as local churches as well.
