I have been told that because I am Messianic and Torah observant that I am a heretic. How do I respond to this claim?
Heresy is a term that can be used by one theological group against another when a belief or teaching espoused by someone is against the belief or teaching that is held by someone else. Sadly, heresy is a term that can be used far too frequently in mainstream Christianity by various denominations or sects to describe others whom they disagree with. However, in many cases the term “heresy” is abused by some who do not understand its correct theological usage.
Baker’s Dictionary of Theology defines “heresy” as “a deliberate denial of revealed truth coupled with the acceptance of error.” Obviously, there are some who see Messianic Believers’ obedience to the Torah and adherence to other things, which are contrary to what mainstream Christianity does, and they consider Messianic Believers to be heretics. However, we as Messianic Believers are not deliberately denying the revealed truth of the Scriptures. Our goal as Messianic Believers is to be fully Biblical from Genesis to Revelation. We do not believe, as many Christians do, that the only applicable Scriptures are the “New Testament,” and we are trying to live a Torah obedient walk of faith like Messiah Yeshua.
If you have been called a heretic by Christian family or friends, then you have legitimate grounds to challenge these people why you are a “heretic,” on the theological basis of what the term heresy means. Challenge these people from the Word of God as to why you are a heretic and how your faith practice differs from what the Scriptures instruct us regarding how to live. Challenge these people and ask them where you have differed with them on the foundational elements of faith such as believing in the Divinity of Yeshua, salvation by grace through faith, or the final authority of Scripture. Oftentimes, you will discover that the terms “heresy” or “heretic” are misapplied by those who do not want to deal with the information that you have for them, and are afraid of investigating it for themselves.
We have a strict policy as a ministry—because how the terms “heresy” and “heretic” can be misused—of only using these terms when it relates to absolute fundamentals of faith and issues which we consider to be salvation oriented.
 M.R.W. Farrer, “Heresy,” in Baker’s Dictionary of Theology, 268.