How long?

 Exodus 6:5-9 AMPC 

5 I have also heard the groaning of the Israelites whom the Egyptians have enslaved; and I have [earnestly] remembered My covenant [with Abraham, Isaac, and Jacob].

6 Accordingly, say to the Israelites, I am the Lord, and I will bring you out from under the burdens of the Egyptians, and I will free you from their bondage, and I will rescue you with an outstretched arm [with special and vigorous action] and by mighty acts of judgment.

7 And I will take you to Me for a people, and I will be to you a God; and you shall know that it is I, the Lord your God, Who brings you out from under the burdens of the Egyptians.

8 And I will bring you into the land concerning which I lifted up My hand and swore that I would give it to Abraham, Isaac, and Jacob; and I will give it to you for a heritage. I am the Lord [you have the pledge of My changeless omnipotence and faithfulness].

9 Moses told this to the Israelites, but they refused to listen to Moses because of their impatience and anguish of spirit and because of their cruel bondage.

When God  sends His Judgement upon us it is not anything man can do or take away. He sent so many things upon the Egyptians that should cause anyone to know that only a person with Supernatural abilities could afflict the people, animals and the land as God did, yet Pharaoh had a hard heart and caused much harm to his own people. God had seen how long (430 years to be exact) the Egyptians, under the leadership of Pharaoh, cruelly treated the Israelites and still felt they were more powerful than God. 

Picture courtesy of Phillip D. Cosby
The rainbow, God’s promise also! 

Yes, being in a situation for that many years, you will think in your mind and heart that things will never change and this is your lot in life. But God caused many things to happen to the Egyptians and not the Israelites to show them He kept His promise to Abraham, Isaac, and Jacob that He would give His people the Promised Land. This is where our test comes, God never tells us when it will happen; nor how long we will suffer a thing to receive His blessings - However, He keeps His Promise! 

His Judgement is again supernatural and are signs for us to turn away from being wicked, change our hearts and live righteous. However, we can’t do that without establishing a relationship with God by daily spending time with Him. We as a nation and world are also hardening our hearts; whereas, as soon as everything calms down (or we think it is) we go back to unjust living and acting. 

We ask, “Why are all these natural disasters coming upon us, as well as diseases, plagues, and pestilence?” Read the book of Exodus and you will find the answer. 

History repeats itself because of our lack of knowledge of God’s Word. 

Hebrews 4:12-13 AMPC 

12 For the Word that God speaks is alive and full of power [making it active, operative, energizing, and effective]; it is sharper than any two-edged sword, penetrating to the dividing line of the breath of life (soul) and [the immortal] spirit, and of joints and marrow [of the deepest parts of our nature], exposing and sifting and analyzing and judging the very thoughts and purposes of the heart.

13 And not a creature exists that is concealed from His sight, but all things are open and exposed, naked and defenseless to the eyes of Him with Whom we have to do.