What is so amazing about the false prophet and teacher is that they are known by others to be Christians (Titus 1:16; Acts 20:30). They can prophesy the words of the Lord (Deuteronomy 13:1‑4; Numbers 22:18‑20, 38; 23:7‑12, 25‑26; 24:2, 9, 13; 2 Peter 2:15; Revelation 2:14), but their lives are full of iniquity. On judgment day these false prophets and teachers will say,
But in reality they will be turned away from God's Kingdom. Jesus tells them why.
These people who call themselves Christians practice lawlessness. They talk the Christian talk, but they don't walk the Christian walk.
What is scary is that they enjoy the fellowship dinners with other Christians (2 Peter 2:13), they will give great sermons and speeches and,
They are among God's people and may be a leader in the church (Acts 20:30; 3 John 1:9). They will introduce secretly (that is, in a way that will be hard to see that they are wrong) damnable heresies. A damnable heresy means, that which can lead to spiritual ruin or destruction. The sad thing about all of this is that,
"Many" is defined as "a large, indefinite number, the masses." This will lead to spiritual ruin and loss because the way of truth will now be scoffed at and ridiculed (2 Peter 2:2).

The Apostle Peter tells us that the false teacher will "deny" the Lord that bought them (2 Peter 2:1). It is not that the false teacher says, "I deny that Jesus is the Christ, the Son of God," etc. The word "deny" means to contradict, or disown Jesus as Lord or Master, the one who has the right to rule and to reign in your life. They disown Jesus' Lordship and also contradict his teaching. I have had people imply, "We don't have to pay attention to Jesus' words because He was under the law" (Galatians 4:4). I have had some tell me not to pay attention to Jesus' words because Paul had the revelation of grace (John 1:17). This kind of talk leads to doctrines like, we never have to confess our sins (1 John 1:9), repentance is a one time act that doesn't need to continue (Acts 8:21‑22), living godly is not important (Hebrews 12:14), faith is not an ongoing event (Colossians 1:23; Luke 8:13), etc.

The truth about saving faith is that it is continuous and taught by both Arminianism and Calvinism theology, although they come from different perspectives.

Calvinism, which professes eternal security, teaches that genuine believers may stumble or fall, but they will nevertheless persevere in the Christian faith (1 Corinthians 1:8). Those who believe in eternal security believe also that true Christians have experienced a death to sin and will not continue in it (Romans 6:1‑3). Those who would later turn completely away from Christ show that they were never truly born again (1 John 2:19).

Arminian theology teaches that genuine believers can fall away from the Christian faith. They generally believe and teach that those who do fall away lose, or forfeit, their salvation. Their system makes no room for so-called Christians (those by name only) to live in continuous rebellion or deliberate sin with no fruit that proves their repentance.

Other heresies that lead to spiritual ruin and destruction include, a misunderstanding of God's grace (Jude 1:4; Romans 6:1), no punishment or judgment (2 Peter 2:9; Acts 24:24‑25), freedom from law or restraints (2 Peter 2:19), etc.

These false teachers and prophets can tell you the facts in the church's creed, but their lifestyle does not pass the test of sound doctrine (1 Timothy 6:3‑4). They have erred from the faith (forsaken and wandered from the truth; James 5:19‑20). They had at one time escaped the pollutions of the world through knowing Jesus as Lord and Savior (2 Peter 2:20), but they turned back, and were overcome by corrupt, immoral living (2 Peter 2:14).

Can they come back and recover? Yes! (2 Timothy 2:24‑26), but they have lost their ability to be an example to the world and to God's people (1 Timothy 3:7).

Why am I sharing these things? Because God helps us stay in sound doctrine by giving us warnings. Don't disregard the warnings. Don't say, "I'm a Christian and this can't happen to me." Jesus one time cursed a fig tree, because it should have had fruit, but on close examination it had none (Matthew 21:19). Jesus said you will know the false prophets by their fruit, by what they do, by what they practice (Matthew 7:15‑20). Perfection no, direction yes!

God gives warnings to His church (Revelation 3). The warnings go out to all. Flee lusts, follow righteousness, so that we may always call on the Lord with a pure heart and conscience (2 Timothy 2:22).