In the last recorded prayer of our lord in the bible, Jesus prayed that we would be one as He and the Father are one.
John 17:21-22 That they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us: that the world may believe that thou hast sent me. (22) And the glory which thou gavest me I have given them; that they may be one, even as we are one:
Unfortunately, there are thousands of protestant denominations. Each one of them separating over points of doctrine. No two people agree on all subjects. Disagreements are unavoidable.
I have never won an argument by raising my voice. This only makes things worse.
Proverbs 15:1 A soft answer turneth away wrath: but grievous words stir up anger.
The best approach I have found is to sincerely try to understand the other person’s point of view. The best way to do that is to ask them if they think you understand their position.
Take a moment, and rephrase their position in different words. Do not simply regurgitate what they said. Then ask them “is that correct?”
Once they feel confident that you understand their position only then can a constructive truth seeking conversation ensue.
Proverbs 27:17 Iron sharpeneth iron; so a man sharpeneth the countenance of his friend.
We must look at these differences of opinions as two friends exploring the truth together and not as adversaries.
As much as I study and pray, I have major theological epiphanies quite often. Ten years ago, I thought I had it down. Looking back, I am astounded by how much more there is to learn about God and His Word. Therefore, when I run into a difference of opinion between someone and myself I know who is sold out to God, I handle it with meekness and fear (1 Peter 3:15).
This scripture comes to mind:
1 Corinthians 10:12 Wherefore let him that thinketh he standeth take heed lest he fall.
We are all at different levels in our relationship with Jesus. Speak softly and let the Sword do most of the talking (Ephesians 6:17).