How you speak is crucial!
There is a way to speak that is key to success in this world; if you want to be successful saturate all your conversations, debates, and disagreements in humility, patience, gentleness, kindness and reasonableness.
However, for the Christian, worldly success is not our first motivation, our first motivation is to do the will of God. It is God's will that ALL speech be humble, patient, kind, gentle, and reasonable - after all that is the definition of love. Love is action, not emotion - if you love someone you will be patient, kind, gentle, and humble with them; you will be reasonable and not insist on your own way.
A child speaks, thinks, and reasons differently than an adult. The same is true of a non-believer or even a "baby" Christian. As children of God, we must grow up, we must mature, we must grow in to the likeness of Christ. The most stark evidence of a mature Christian is that they speak, think, and reason with love.
1Corinthians 13:1 If I speak in the tongues of men and of angels, but have not love, I am a noisy gong or a clanging cymbal.
1Corinthians 13:4-5 Love is patient and kind; love does not envy or boast; it is not arrogant 5 or rude. It does not insist on its own way; it is not irritable or resentful;
2Corinthians 3:18 And we all, with unveiled face, beholding the glory of the Lord, are being transformed into the same image from one degree of glory to another. For this comes from the Lord who is the Spirit.