Heresy is one of the churches greatest enemies and has been such since the beginning of the Lord's Church. Romans 16:17 and 1 Timothy 1:10 warn churches to recognize, mark, and avoid those that preach and practice heresy.
Heresy abounds today and must be recognized, marked, and avoided. Many of today's most popular preachers and pastors are those whose teaching is heresy. 
Who am I to make such a statement? I am no one; but God's Word is Truth and teaching/preaching that does not line up with Scripture is heresy, a contrary doctrine. 
We as saints must be able to tell the difference between Truth and fiction-especially spiritually. It does not matter how large a church one pastors or how many books they have written. It does not matter that "some" of what is taught is Truth-that is the most dangerous type of heresy. 
. We are quick to use Scripture such as 2 John vs. 10 to not allow these heretical teachers in our doorway at our homes; yet their books are on our book shelves, their radio programs are playing in our cars, and their broadcasts are on our television sets. We must beware!Heresy is nothing new, for it, as the church, has a long history. We first find heresy in the Judaism attempting to infiltrate the early churches. In Acts 15 there was a false teaching being introduced into the church that one must be circumcised or "ye cannot be saved." The Jews were used to rituals, and many that were saved found it difficult to leave their old customs. This false teaching was immediately exposed and corrected (vs. 11) "But we believe that through the grace of the Lord Jesus Christ we shall be saved, even as they." According to Doug Hammett in The History of Baptist,"there were three groups of Jewish 'Christians' with Judaistic tendencies:
1. Nazarenes-represented by the more 'moderates.' They maintained customs but accepted Paul's ministry.
2. Ebionites-openly taught the need for strict observance of law by all Christians. They ultimately came to reject Paul and his writings and developed the doctrine of Unitarianism.
3. Elkesaites-more of a secret society, philosophic and ascetic. The denied the deity of Christ."
The early foundation for cults were being laid down: works salvation, denying of Scripture, and rejecting the deity of Christ.
The Nicolaitanes are mentioned in Rev. 2:6, 15 as believing "which thing(s) I hate." The Lord recognized, marked, and told us to avoid such. Who were the Nicolatians? Their name means 'to conquer the people.' There false teaching was that of church hierarchy which the Catholics and such ran with. (there are sadly many 'dictatorial pastors' in Baptist churches today as well). It is the Church who our Lord has given the authority to.
Another heresy early was Gnosticism. Gnosticism was addressed by Paul in the book of Colossians greatly. It had its origins in Judaism and developed into a mixture of religious philosophy. The word 'Gnostic' means "I know". Gnostics believed they had special knowledge above that of normal believers. How this abounds today-ask Joseph Smith, Mary Eddy, Mohammad, Oral Roberts followers. They will tell you about their 'special knowledge.'
The heresy of Balaamism (Rev. 2:14). Balaam's doctrine was that of corruption, mixing paganism and pure religion. This abounds today in the inter/non denominational 'any thing goes' churches; Catholicism; and worldliness centered 'churches.'
One could talk of the Traditions and philosophies that were being introduced into churches-but the bottom line is this: Heresy was infiltrating the church early. Christians were warned immediately to recognize, mark, and avoid heresy. Those in the early church were characterized by 'proving' and 'preaching' Truth. Sadly today, we step around and dumb down Truth. Our 'offend nobody' philosophy does not work well with the Biblical command to separate.
Heresy has been around the church since the church's beginning, and continues to abound today; we must know the Truths of the Word of God and stand strong!
