Well lets start with Abraham, since we all know about Him.To predestine means to destine/determine something beforehand.
Gen 17:1 And when Abram was ninety years old and nine, the LORD appeared to Abram, and said unto him, I am the Almighty God; walk before me, and be thou perfect.
Gen 17:2 And I will make my covenant between me and thee, and will multiply thee exceedingly.
Gen 17:3 And Abram fell on his face: and God talked with him, saying,
Gen 17:4 As for me, behold, my covenant is with thee, and thou shalt be a father of many nations.
Gen 17:5 Neither shall thy name any more be called Abram, but thy name shall be Abraham; for a father of many nations have I made thee.
Gen 17:6 And I will make thee exceeding fruitful, and I will make nations of thee, and kings shall come out of thee.
Gen 17:7 And I will establish my covenant between me and thee and thy seed after thee in their generations for an everlasting covenant, to be a God unto thee, and to thy seed after thee.
Now was Abraham perfect
Seems he feared man more than God, so He was not perfect.
Gen 20:1 And Abraham journeyed from thence toward the south country, and dwelled between Kadesh and Shur, and sojourned in Gerar.
Gen 20:2 And Abraham said of Sarah his wife, She is my sister: and Abimelech king of Gerar sent, and took Sarah.
Oh nad His wife gave Him her servant Girl becuase she didnt believe she would have her own child, so here we see Abrham again, not perfect
Gen 21:9 And Sarah saw the son of Hagar the Egyptian, which she had born unto Abraham, mocking.
Gen 21:10 Wherefore she said unto Abraham, Cast out this bondwoman and her son: for the son of this bondwoman shall not be heir with my son, even with Isaac.
Gen 21:11 And the thing was very grievous in Abraham's sight because of his son.
Gen 21:12 And God said unto Abraham, Let it not be grievous in thy sight because of the lad, and because of thy bondwoman; in all that Sarah hath said unto thee, hearken unto her voice; for in Isaac shall thy seed be called.
Gen 21:13 And also of the son of the bondwoman will I make a nation, because he is thy seed
See Abraham was predestined to be the father of many nations, God gave Him choice and He messed up, how many countless times we dont know, yet God who is faithfull still Kept His promse. Than one can look at david and all he did, yet even He still found favour with God and God still kept His promise. Why do people have no faith in God, is that not what Christanity is all about.