Ephephesians 4: 14-16
14 Then we will no longer be immature like children. We won’t be tossed and blown about by every wind of new teaching. We will not be influenced when people try to trick us with lies so clever they sound like the truth. 15 Instead, we will speak the truth in love, growing in every way more and more like Christ, who is the head of his body, the church. 16 He makes the whole body fit together perfectly. As each part does its own special work, it helps the other parts grow, so that the whole body is healthy and growing and full of love.
Jesus is Love. It is so tempting to share our thoughts and opinions with people, especially if it is something we feel strongly about, but it is important to remember to speak the truth in love. I personally receive things better when I feel like they are spoken to me kindly, and with respect- even if I don't agree. Being snarky, harsh, cold, or snappy will just cause others to be defensive, and miss the reason you were sharing the truth with them (usually because you love them, and want what is best for them.)
Your message will always be received better when it is spoken with love.
It is also important to know truth in the Bible before you go blabbering on about something you heard once (or all your life.)
John 8: 31-32
31 Jesus said to the people who believed in him, “You are truly my disciples if you remain faithful to my teachings. 32 And you will know the truth, and the truth will set you free.”
Only by really delving into scripture (like you would research anything else,) will you be able to really know truth. Remember how you could not turn in a paper in school with quotes in it, unless the quotes were cited? Be prepared to cite your quotes by memorizing scripture. Just saying, "it's in the Bible," is not a good enough answer for children or adults.