When the Bible says that all have sinned it means that every man, woman, and child who has ever lived has failed to fully obey the laws of God. This means that everyone is a sinner.

"For all have sinned, and come short of the glory of God." (Romans 3:23)

In these days and times, it is necessary to further explain sin.  Sin is the bad things we say, think, or do.  It is also the good things we should do, but don't.   Any act, word, or thought that is not in complete accordance with God's Word is sin.  This is in conflict with the beliefs of our times: If it feels good, do it; Believe what you want, as long as you are sincere; I'll do it my way; As long as your good deeds outweigh your bad deeds; I'm not as bad as everyone else.  All of these are based on human views and beliefs.  The concept of sin comes from God.  God is holy, and cannot tolerate sin.   

You may be someone who is living a moral life, or who has done great kindness to others. You are a sinner under the judgment and the penalty of sin. You may be someone living an immoral life. You also are a sinner facing the penalty of sin. The law of God makes no exceptions: all who violate God's law in any way are sinners and face the penalty for that sin.

"They are all gone out of the way, they are together become unprofitable; there is none that doeth good, no, not one." (Romans 3:12)

Have you ever said something that is not true? Then you are a liar.

"Ye are of your father the devil, and the lusts of your father ye will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father of it." (John 8:44)

Have you ever taken something that does not belong to you? Then you are a thief or a robber.

"For from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders, Thefts, covetousness, wickedness, deceit, lasciviousness, an evil eye, blasphemy, pride, foolishness: All these evil things come from within, and defile the man." (Mark 7:21-23)

Have you ever wished in your heart that someone was dead? Then you are a murderer.

"Whosoever hateth his brother is a murderer: and ye know that no murderer hath eternal life abiding in him." (I John 3:15)

Have you ever looked at someone else with lust in your heart? Then you are an adulterer.

"Ye have heard that it was said by them of old time, Thou shalt not commit adultery: But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart." (Matthew 5:27-28)

God doesn't play games; He doesn't "spin" anything. He doesn't put our works on a scale to see if the good outweighs the bad. It is an all-or-nothing judgment: either we have kept perfectly the law of God, or we haven't. If we haven't, and none of us have, we are sinners. Sinners facing what we have earned, The Wages of Sin.