I will bet that no one has ever asked you that question. Unless you have studied theology, you probably never heard that term. Gnostics were a group of people who lived during the time of Jesus Christ. They believed that the flesh (body) was evil and the spirit was good. Since the body was evil, then it was not possible for Jesus Christ to have a physical body. That would make Him evil. They thought He was some kind of spirit being. The main reason for the Apostle John to write the Epistles of John was refute this heresy. “That which was from the beginning, which we have heard, which we have seen with our eyes, which we have looked at and our hands have touched… The life appeared; we have seen it and testify to it,…[ 1 John 1:1-2] They could (according to them) live a very sinful lifestyle but it would not affect them spiritually. They had conveniently separated the body and the spirit.
But what has that to do with you 2,000 years later? There are multitudes that attend church every time the doors are open. They read their Bibles, volunteer to do things in the church and testify that Jesus Christ is their Lord and Savior. But the remainder of the week they live like they want. Like the Gnostics, they separate their church life and their life outside the church. But the Bible clearly teaches you cannot separate secular (outward) and spiritual (inward.) “So whether you eat or drink, or whatever you do, do it all for the glory of God.”
Unchurched people are quick to notice how we act on the job and what we profess at church. Your outward life is a natural expression of the inner experience. Nothing hinders the Gospel more than a Christian that does not ‘walk the talk.’