Psalm 103 – Skeptic's Annotated Bible answered

1 Bless the LORD, O my soul: and all that is within me, bless his holy name.

2 Bless the LORD, O my soul, and forget not all his benefits:

3 Who forgiveth all thine iniquities; who healeth all thy diseases;

"The Lord ... who healeth all thy diseases."
God heals all diseases. Medical science is unnecessary.
What the Bible says about medical science

4 Who redeemeth thy life from destruction; who crowneth thee with lovingkindness and tender mercies;

5 Who satisfieth thy mouth with good things; so that thy youth is renewed like the eagle’s.

6 The LORD executeth righteousness and judgment for all that are oppressed.

7 He made known his ways unto Moses, his acts unto the children of Israel.

8 The LORD is merciful and gracious, slow to anger, and plenteous in mercy.

"The Lord is merciful and gracious, slow to anger, and plenteous in mercy."
Is this the same guy who demanded that peoples' heads be hung up before him to appease his fierce anger (Num.25:4), and who ordered the slaughter of thousands of innocent men, women, children (1 Sam.15:2-3)?
Is God merciful?

9 He will not always chide: neither will he keep his anger for ever.

10 He hath not dealt with us after our sins; nor rewarded us according to our iniquities.

11 For as the heaven is high above the earth, so great is his mercy toward them that fear him.

(103:11, 12, 17) God has mercy on those that fear him.
Should we fear God?

12 As far as the east is from the west, so far hath he removed our transgressions from us.

13 Like as a father pitieth his children, so the LORD pitieth them that fear him.

14 For he knoweth our frame; he remembereth that we are dust.

15 As for man, his days are as grass: as a flower of the field, so he flourisheth.

16 For the wind passeth over it, and it is gone; and the place thereof shall know it no more.

17 But the mercy of the LORD is from everlasting to everlasting upon them that fear him, and his righteousness unto children’s children;

18 To such as keep his covenant, and to those that remember his commandments to do them.

19 The LORD hath prepared his throne in the heavens; and his kingdom ruleth over all.

20 Bless the LORD, ye his angels, that excel in strength, that do his commandments, hearkening unto the voice of his word.

21 Bless ye the LORD, all ye his hosts; ye ministers of his, that do his pleasure.

22 Bless the LORD, all his works in all places of his dominion: bless the LORD, O my soul.