Symptoms Of The Lost
First some good news: Luke 19:10: For the Son of man is come to seek and to save that which was lost.
One of the first symptoms of the lost is that they have no interest in the eternal destiny of others. I trust that is not your attitude. Christians are often described as servants of God. If we are servants of God we will seek to be instruments in His endeavor to seek the lost.
Daniel 12:3: And they that be wise shall shine as the brightness of the firmament; and they that turn many to righteousness as the stars for ever and ever.
Proverbs 11:30: The fruit of the righteous is a tree of life; and he that winneth souls is wise.
James 5:20: Let him know, that he which converteth the sinner from the error of his way shall save a soul from death, and shall hide a multitude of sins.
Romans 11:14: If by any means I may provoke to emulation them which are my flesh, and might save some of them.
1 Corinthians 9:22: To the weak became I as weak, that I might gain the weak: I am made all things to all men, that I might by all means save some.
1 Timothy 4:16: Take heed unto thyself, and unto the doctrine; continue in them: for in doing this thou shalt both save thyself, and them that hear thee.
If those scriptures speak about you or if you wish they did the first thing you will need to learn is who are the saved and who are the lost. When you believe that someone is among the lost you will want them to be saved. You will want the Lord Jesus to save them and you will be willing to help in any way that He wants you to. You will have some jobs to do. One will be to pray for them. One will be to live a joyful and righteous life before them. One will be to tell them what the Lord has done for you. One will be to quote the Bible to them. One MIGHT BE to lead them to Christ yourself. There are some helpful suggestions for how to do that under the subtopic Evangelism or the letter H in the alphabetical index.
You CAN discover if a person is lost. You can never look upon their heart and know for sure but it will be obvious at least 90% of the time. When people are repeatedly unkind to us or to others we need to get past the offense and recognize that they are simply telling us a very important thing about themselves. They are telling us that they are LOST! It is almost as if they light up a sign on their forehead that blazes out in bright colors: I NEED THE JESUS! I NEED LOVE! PLEASE GIVE ME THE GOSPEL!
Some of the neon signs they will exhibit: hatred, apathy, anger, self-centeredness, addictions, profanity, pride, loneliness, cruelty, sick sense of humor, isolationism, dishonesty, fears, misguided, stubborn, part of a cult, part of an unbiblical church, out-of-control, hard-hearted, domineering, wordy, immoral priorities, greedy, violent, spiritually blind, enemies of self, seared conscience, prejudice, confusion, stingy, no interest in the Bible, etc.