What is blasphemy and heresy?

Many of us who "grew up in the church" are familiar with words like  blasphemy and heresy, but aren't sure what they mean,  how God applies them in His word, and how He expects us to apply them in our daily lives as His holy and dearly loved children.
"You shall not take the name of the LORD your God in vain, for the LORD will not hold him guiltless who takes His name in vain."
~ Exodus 20:7

"But false prophets also arose among the people, just as there will be false teachers among you, who will secretly bring in destructive heresies, even denying the Master who bought them, bringing upon themselves swift destruction."
2 Peter 2:1

In order to gain what God's usage of blasphemy and heresy are, we'll take a look at how these words (in their various forms) are used in Scripture as well as the original Hebrew and Greek.

blasphemy n. ~ 1. profane or contemptuous speech, writing, or action concerning God or anything held as divine; 2. any remark or action held to be irreverent or disrespectful.

heresy n. ~ 1. a religious belief opposed to the orthodox doctrines of a church; esp., such a belief specifically denounced by the church; 2. any opinion (in philosophy, politics, etc.) opposed to official or established views or doctrine.

Deuteronomy 5:11
"You shall not take the name of the LORD your God in vain, for the LORD will not hold him guiltless who takes His name in vain."

vain ~ [Hebrew] shav' means: emptiness, vanity, falsehood; or shav {shav}; from the same as 7722 in the sense of desolating; evil (as destructive), literally (ruin) or morally (especially guile)

Leviticus 24:16
"Whoever blasphemes the name of the LORD shall surely be put to death. All the congregation shall stone him. The sojourner as well as the native, when he blasphemes the Name, shall be put to death."

blaspheme ~ [Hebrew] naqab means: to pierce, perforate, bore, appoint; a primitive root; to puncture, literally (to perforate, with more or less violence) or figuratively (to specify, designate, libel):-appoint, blaspheme, bore, curse, express, with holes, name, pierce, strike through

1 Timothy 1:18-20
"This charge I entrust to you, Timothy, my child, in accordance with the prophecies previously made about you, that by them you may wage the good warfare, holding faith and a good conscience. By rejecting this, some have made shipwreck of their faith, among them are Hymenaeus and Alexander, whom I have handed over to Satan that they may learn not to blaspheme."

Jude 1:8
"Yet in like manner these people also, relying on their dreams, defile the flesh, reject authority , and blaspheme the glorious ones."

blaspheme ~ [Greek] blasphemeo means: to speak reproachfully, rail at, revile, calumniate, blaspheme

2 Peter 2:1-3
"But false prophets also arose among the people, just as there will be false teachers among you, who will secretly bring in destructive heresies, even denying the Master who bought them, bringing upon themselves swift destruction. And many will follow their sensuality, and because of them the way of truth will be blasphemed. And in their greed they will exploit you with false words. Their condemnation from long ago is not idle, and their destruction is not asleep."

heresies ~ [Greek] hairesis means: a body of men following their own tenets (sect or party); false teaching; division

"Then I saw heaven opened, and behold, a white horse! The one sitting on it is called Faithful and True, and in righteousness He judges and makes war. His eyes are like a flame of fire, and on His head are many diadems, and He has a name written that no one knows but himself. He is clothed in a robe dipped in blood and the name by which He is called is The Word of God."
~ Revelation 19:11-13 (emphasis added)

When Moses asks God what His name is, God simply tells Moses, "I AM WHO I AM" (Exodus 3:14-15). This was a very significant and profound point God made to Moses as he was aware that those who worshiped false gods, gave their god a name depending on what service that specific god provided the people. But our God, the one true God has no name given to Him by man.

Unlike the pagan gods, we did not create the Lord God Almighty; therefore we cannot presume that we are capable of giving Him a name apart from the names He uses in Scripture, nor add or take away from His holy character.

Attempting to give God a name, use his name in vain, that is, with no purpose (e.g. "Oh my G-d!"), or describe His character in a manner that He has never given us to use, is to be guilty of blasphemy.

Then there's the word "heresy". What does it mean to commit this sin? From Scripture we can clearly understand that heresy is the opposite of sound doctrine, it is false doctrine. But then the question has arisen (especially within the emerging or emergent church movement) that doctrine is not important, only relationship is important, so why teach doctrine? To answer that question, let's see what God says about doctrine.

"Now we know that the law is good, if one uses it lawfully, understanding this, that the law is not laid down for the just but for the lawless and disobedient, for the ungodly and sinners, for the unholy and profane, for those who strike their fathers and mothers, for murderers, the sexually immoral, men who practice homosexuality, enslavers, liars, perjurers, and whatever else is contrary to sound doctrine, in accordance with the gospel of the glory of the blessed God with which I have been entrusted."
~ 1 Timothy 1:8-11 (emphasis added)

"He must hold firm to the trustworthy word as taught, so that he may be able to give instruction in sound doctrine and also to rebuke those who contradict it."
~ Titus 1:9 (emphasis added)

According to Scripture, sound doctrine is very important and we, as God's holy children ought to teach and learn sound doctrine and gently reprove or strongly rebuke (depending in the situation) those who teach what is contrary.

Sound doctrine is teaching what is in agreement with Scripture. In other words, if it's not in God's word, then it's not "sound". Not only this, but we must be sure to read God's word through His eyes, and not ours. How can we do this? Through the power of the Holy Spirit.

"For who knows a person's thoughts except the spirit of that person, which is in him? So also no one comprehends the thoughts of God except the Spirit of God. Now we have received not the spirit of the world, but the Spirit of God, that we might understand the things freely given us by God. And we impart this in words not taught by human wisdom but taught by the Spirit, interpreting spiritual truths to those who are spiritual."
~ 1 Corinthians 2:11-13

Before I was taught this truth, there were times I had a thought or opinion about something, then I'd pick and choose Scriptures I believed supported my personal ideology. The only problem with that is that we're supposed to follow God's word, not the other way around. Having an opinion about something, then opening God's word to see if you can find support for it, is never the way to read God's word. Doing this puts many of us in the dangerously tempting place of learning and teaching false doctrine as we begin to slowly take God's word out of the context in which He intended and begin to read and apply it in the context of our emotions, thoughts or personal experiences.

In conclusion, blasphemy is using God's name or referring to His character with no reverence or for no purpose (i.e., speaking to God as if He is our equal, using profanity or other vulgar language before His sight or in relation to His holy name and character).

Heresy is any teaching that did not originate from the infallible, inerrant word of God, but from vain human philosophies or ideologies that are found nowhere in the holy Scriptures. God's word is complete and needs no additions or subtractions nor the help of man to make God's message more palatable for the hearers (2 Tim 4:3-4).

"For Christ did not send me to baptize but to preach the gospel, and not with words of eloquent wisdom, lest the cross of Christ be emptied of its power."
~ 1 Corinthians 1:17