NOTE: This one is a bit long because I felt it important to include the full text of the scriptures I referenced. I hope you find the included Bible verses helpful.
The scriptures tell us that words are serious business. Read what Jesus has to say about the words we speak, “I tell you, on the day of judgment people will give account for every careless word they speak, for by your words you will be justified, and by your words you will be condemned.” (Matthew 12:36–37 (ESV)) But it’s not just judgment. Words are serious in how beautiful and valuable they can be. The scriptures tell us that, “A word fitly spoken is like apples of gold in a setting of silver.” (Proverbs 25:11 (ESV))
As we examine the scriptures, you might notice that there is no prescription for a Christian to litter their speech with Christian-sounding phrases such as, “Praise the Lord!” The only place I can find where words are prescribed is when Jesus taught his disciples to pray with the words of the Lord’s Prayer. But there are many descriptions of how the people of God speak, both positive and negative.
Christians speak with praise to God. (Psalm 34:1 (ESV) I will bless the LORD at all times; his praise shall continually be in my mouth.)
Christians speak graciously. The roots from which the Greek word for “gracious” is derived include concepts of giving and joy.  (Colossians 4:6 (ESV) Let your speech always be gracious, seasoned with salt, so that you may know how you ought to answer each person.)
Christians speak words of blessing. (Romans 12:14 (ESV) Bless those who persecute you; bless and do not curse them.)
Christians speak gently. (Proverbs 15:1 (ESV) A soft answer turns away wrath, but a harsh word stirs up anger. Proverbs 15:4 (ESV) A gentle tongue is a tree of life, but perverseness in it breaks the spirit.)
Christians speak encouragingly. (1 Thessalonians 4:18 (ESV) Therefore encourage one another with these words.)
Christians speak with patience and kindness. (1 Corinthians 13:4–5 (ESV) Love is patient and kind; love does not envy or boast; it is not arrogant or rude. It does not insist on its own way; it is not irritable or resentful;)
Christians do not speak dishonestly. (Proverbs 6:16–19 (ESV) There are six things that the LORD hates, seven that are an abomination to him: …a lying tongue, …a false witness who breathes out lies, and one who sows discord among brothers.) Note that the phrase, “there are six… seven,” is a way to highlight something. It’s like texting in ALL CAPS WITH MULTIPLE EXCLAMATION POINTS!!!
Christians do not speak deceptively or manipulatively. Christians are straight talkers. (Proverbs 4:24 (ESV) Put away from you crooked speech, and put devious talk far from you.)
Christians don’t need to go on and on when they are speaking. (Proverbs 10:19 (ESV) When words are many, transgression is not lacking, but whoever restrains his lips is prudent.)
Christians do not speak crudely. (Ephesians 5:4 (ESV) Let there be no filthiness nor foolish talk nor crude joking, which are out of place, but instead let there be thanksgiving. Colossians 3:8 (ESV) But now you must put them all away: anger, wrath, malice, slander, and obscene talk from your mouth.)
Christians do not speak boastfully, arrogantly, rudely, irritably, or resentfully. (1 Corinthians 13:4–5 (ESV) Love is patient and kind; love does not envy or boast; it is not arrogant or rude. It does not insist on its own way; it is not irritable or resentful;)
It’s not simply the words themselves that are important. Words can be empty. Matthew 6:7 (ESV) “And when you pray, do not heap up empty phrases as the Gentiles do, for they think that they will be heard for their many words.
The intention of the speech is just as important as the words used. The Bible tells us that people can utter the right words without their heart being in the right place. (Matthew 7:21 (ESV) “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven.) People use words to hide their true motives and manipulate situations. (Psalm 55:20 – 21 (ESV) My companion stretched out his hand against his friends; violated his covenant. His speech was smooth as butter, yet war was in his heart; his words were softer than oil, yet they were drawn swords.)
It turns out that our words are not the real problem. The way we speak is really a diagnostic tool to discern the deeper condition of our hearts, like a thermometer helps to discern the inner temperature of a body.
Jesus teaches us that if our words are problematic, the words are not the real problem. If you have a speech problem, you really have a heart problem because your words flow out of your inner life. (Matthew 15:17–20 (ESV) Do you not see that whatever goes into the mouth passes into the stomach and is expelled? But what comes out of the mouth proceeds from the heart, and this defiles a person. For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false witness, slander. These are what defile a person. But to eat with unwashed hands does not defile anyone.”) (See also Matthew 12:34; Luke 6:45)
Honestly, it’s not really a question of if you have a speech problem, but when you have a speech problem. When you have a speech problem, your heart is not in the right place. So your heart is where the treatment needs to start.
The Bible gives us a very clear course of treatment for spiritual heart problems.
Step one is confession. When we run from or conceal our sin, we are blocking the cleansing and renewal God wants to give us. (1 John 1:8–9 (ESV) If we say we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.)
Step two is repent. The Greek root for “repentance” indicates that we turn our thinking around. We let go of our selfish thoughts and embrace God’s thoughts. Jesus called it losing your life for his sake. (Luke 24:45–47 (ESV) Then [Jesus] opened their minds to understand the Scriptures, and said to them, “Thus it is written, that the Christ should suffer and on the third day rise from the dead, and that repentance and forgiveness of sins should be proclaimed in his name to all nations, beginning from Jerusalem.)
Step three is live in faith. Faith trusts God’s promise that forgiveness is complete in Jesus, that we are God’s children and live in God’s love. (John 3:16 (ESV) For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life.) It is this forgiveness and love from God toward us that will empower us to speak like a Christian as a natural consequence of what’s going on inside of us.
For all those who want to really speak like a Christian instead of simply adopt Christian-sounding phrases, here are four steps for speaking like a Christian.
One, consider the person before you speak. Often our speech degenerates when our view of the other person degenerates. As much as you may not like or feel hurt by (or whatever) the person to whom or about whom you are speaking, pause to remember that the other person is dearly loved by God… as dearly as you are. (1 Timothy 2:4 (ESV) [God] desires all people to be saved and to come to the knowledge of the truth.) Reflect on God’s kindness toward you as you consider the other person. (Ephesians 4:32 (ESV) Be kind to one another, tenderhearted, forgiving one another, as God in Christ forgave you.) Picture that person as dearly loved by God in whatever way helps you. Imagine a little glow around them. See a shaft of light piercing the heavens and landing on their head. Picture them at the foot of the cross.
Two, listen first. The scriptures tell us that it is quite foolish to answer before you have all the information. (Proverbs 18:13 (ESV) If one gives an answer before he hears, it is his folly and shame. Proverbs 29:20 (ESV) Do you see a man who is hasty in his words? There is more hope for a fool than for him.) James tells us that Christians are “quick to hear, slow to speak, slow to anger.” (James 1:19)
Three, consider your words before you speak. This may seem obvious, but the Bible tells us to think about the words we are about to say and then choose, based on scriptural teaching, wisdom, love and the guidance of the Holy Spirit, whether we should actually utter the words we are considering. (Ephesians 4:29 (ESV) Let no corrupting talk come out of your mouths, but only such as is good for building up, as fits the occasion, that it may give grace to those who hear. Proverbs 15:28 (ESV) The heart of the righteous ponders how to answer, but the mouth of the wicked pours out evil things. Proverbs 12:18 (ESV) There is one whose rash words are like sword thrusts, but the tongue of the wise brings healing.) James goes so far as to tell us that controlling our tongue is a core part of new life in Christ. (James 1:26 (ESV) If anyone thinks he is religious and does not bridle his tongue but deceives his heart, this person’s religion is worthless.)
Four, speak with restraint. The scriptures tell us that it is wisdom not to overflow with words. (Proverbs 17:27 (ESV) Whoever restrains his words has knowledge, and he who has a cool spirit is a man of understanding. Proverbs 10:19 (ESV) When words are many, transgression is not lacking, but whoever restrains his lips is prudent.)
The idea of speaking like a Christian does include the words you use, but it has nothing to do with adopting Christian-sounding, pious phrases. It has everything to do with a repentant and grateful heart that rests in God and seeks to spread the love of Christ to all people in all situations.