Ye shall know them by their fruits

So many people confess Jesus as their Lord and saviour yet produce both good and bad fruit, how are we to tell who is on the Lord's side? Satan is to come as an angel of light, and his ministers appear as from the light as well, what are we to do?
We need to spend some time to read over and think on these subjects to get those answers.

The fruit to look for is obedience to the Law of God.
Matthew 7:15-27
"15Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves. 16Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles? 17Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit. 18A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit. 19Every tree that bringeth not forth good fruit is hewn down, and cast into the fire. 20Wherefore by their fruits ye shall know them.

21Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven. 22Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works? 23And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.

24Therefore whosoever heareth these sayings of mine, and doeth them, I will liken him unto a wise man, which built his house upon a rock: 25And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock. 26And every one that heareth these sayings of mine, and doeth them not, shall be likened unto a foolish man, which built his house upon the sand: 27And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell: and great was the fall of it."