As we read the Bible, we see plainly that it tells us judgment is certain.
"God will judge his people". (Heb. 10:30)
He has appointed a day, (can also be translated, time) in the which he will judge the world in righteousness by that Man whom he has ordained; He has given assurance of this to all men, by raising him from the dead.
. . .Which show the work of the law written in their hearts,...In the day when God shall judge the secrets of men by Jesus Christ according to my gospel.
Some will be judged and awarded everlasting life, others will be judged and sentenced to everlasting destruction. (See John 5:28,29)
Will God execute judgment without an investigation or trial?
We are all charged with treason against God's government.
Romans 3:19 "Now we know that what things soever the law saith, it saith to them who are under the law: that every mouth may be stopped, and all the world may become guilty before God." We are all guilty, unless we repent, confess, and have Christ's blood cover those sins and cleanse us as we walk and live for Him.
Who has united their lives fully with Christ? Who has availed themselves of Christ's provisions of forgiveness and surrendered their sins and their lives to Him? Outward appearance can be deceiving, what are the facts in this judgment?
That is why investigation is important. It lays out the facts so all know that when the judgment is executed it is fair and just. Those whose sins have been confessed and repented of, those whose lives are surrendered to God, have nothing to fear from the investigative judgment.
Throughout the Bible we see that God investigates before he executes judgment.
Let's look at stories in scripture:
King Belshazzar is throwing a big party. He's praising his idols and tops it all off by bringing in the temple dishes and desecrates them. God is about to execute judgment.
But notice all that God has done first.
"You were weighed in the balances and found wanting." In other words— your case was investigated and you were found guilty. "You knew all that God had done for Nebuchadnezzar but you refused to humble your heart.
"And the Lord said, My Spirit shall not strive with man forever, . . .
Gen. 6:5 "Then God saw that the wickedness of man was great on the earth."
God is beginning His investigation.
Gen. 6:11 God looked upon the earth and indeed it was corrupt.
But God investigates even closer:
Gen 6:5 Every intent and thought was evil continually"
Gen.6:9 But Noah was a just man, perfect in generation. Noah walked with God.
Why did Noah Find grace in the eyes of God (vs 8) at this point? Didn't God already know Noah was walking with Him? Of course God knew, but He wanted all the succeeding generations to know why he destroyed the others and made an exception for Noah.
There's the story of Sodom
The Lord said, "I will go down now and see whether they have done altogether according to the cry of it. . ."
Before Sodom was destroyed, God investigated.
Tower of Babel
Genesis 11:5 And the LORD came down to see the city and the tower, which the children of men builded.
Before judgment was executed and the languages confused, God investigated.
Why does God investigate doesn't He know who belongs to Him? Of course he knows — but we don't know and the angels don't know may not know, and the created beings in the universe don't know. There is a lot of religion, many profess to be on the right side, but who are the real believers?
God wants everyone to see the justice of His decisions on who is saved and who is not.