Do I know God’s Word?

It is true that I am an ordinary, weak human being, but I don't use human plans and methods to win my battles. I use God's mighty weapons, not those made by men, to knock down the devil's strongholds. These weapons can break down every proud argument against God and every wall that can be built to keep men from finding him. With these weapons, I can capture rebels and bring them back to God and change them into men whose hearts' desire is obedience to Christ. - 2 Corinthians 10:3-5 (Living Bible)

He must hold firmly to the trustworthy word [of God] as it was taught to him so that he will be able both to give accurate instruction in sound [reliable, error-free] doctrine and to refute those who contradict [it by explaining their error]. - Titus 1:9 (Amplified Bible)

Am I prepared to identify and refute false doctrine?

As the Scriptures say, "I will destroy the wisdom of the wise and discard the intelligence of the intelligent." So where does this leave the philosophers, the scholars, and the world's brilliant debaters? God has made the wisdom of this world look foolish. Since God, in his wisdom, saw to it that the world would never know him through human wisdom, he has used our foolish preaching to save those who believe. It is foolish to the Jews, who ask for signs from heaven. And it is foolish to the Greeks, who seek human wisdom. So when we preach that Christ was crucified, the Jews are offended, and the Gentiles say it's all nonsense. - 1 Corinthians 1:19-23 (NLT)

In recent years, numerous ungodly philosophies and teachings have infiltrated our society and many churches, such as social justice, CRT, permissive grace, gender identity, and liberal Christianity. These teachings, the wisdom of the world, hold people in bondage and become spiritual "fortresses" which blind people to the message of the Gospel. As transformed followers of Christ, it is critical that our awareness of these ungodly teachings is elevated to the point of both recognizing and refuting them when presented. Since they originate from the prince of darkness, the devil himself, it is imperative that we have effectively armed ourselves with the Word of God, the sword of the Spirit, our weapon to confront error and defend the faith.

Do I know the Word of God well enough to defend the Gospel?

These remarks of mine about the Antichrist are pointed at those who would dearly love to blindfold you and lead you astray. But you have received the Holy Spirit, and he lives within you, in your hearts, so that you don't need anyone to teach you what is right. For he teaches you all things, and he is the Truth, and no liar; and so, just as he has said, you must live in Christ, never to depart from him. - 1 John 2:26-27 (Living Bible)

What is the best safe-guard against false teaching? 
Beyond all doubt the regular study of the word of God, with prayer for the teaching of the Holy Spirit.
The Bible was given to be a lamp to our feet and a light to our path (Psalm. 119:105). The man who reads it aright will never be allowed greatly to err. It is neglect of the Bible which makes so many a prey to the first false teacher whom they hear. They would have us believe that "they are not learned, and do not pretend to have decided opinions." The plain truth is that they are lazy and idle about reading the Bible, and do not like the trouble of thinking for themselves. Nothing supplies false prophets with followers so much as spiritual sloth under a cloak of humility. - J.C. Ryle

For the word of God is living and active and full of power [making it operative, energizing, and effective]. It is sharper than any two-edged sword, penetrating as far as the division of the soul and Spirit [the completeness of a person], and of both joints and marrow [the deepest parts of our nature], exposing and judging the very thoughts and intentions of the heart. And not a creature exists that is concealed from His sight, but all things are open and exposed and revealed to the eyes of Him with whom we have to give account. - Hebrews 4:12-13 (Amplified Bible)

Be Encouraged to arm yourself with the Word of God and proactively defend the Gospel. 

-Jeffrey Thornton