Catechism by tnap

Puzzle explanation

The corrections to clue misprints spelt out “Raffiniert ist der Herrgott, aber boshaft ist er nicht” (God is subtle but he is not malicious), a statement made by Albert Einstein. His theory of Special Relativity predicted length contraction (represented by four entries having LLL replaced by L), time dilation (four entries having T replaced by TTT), and mass-energy equivalence according to E = mc2 (four entries being jumbled with E replacing MCC). Treating the title similarly gives ATHEISE.

Clue explanations

Conventions: * = anagram, < = reversal

Across
1 fa(R) ASANA AS + AN + A
6 pinn(A) SHELL-LIKE SHE’LL + LIKE
11 (F)ight VISITE SIT in VIE
14 (F)ore ECOFIN (CONFINE − N) with E moved to the start
15 Fruit(I)ly ANTON (w)ANTON
16 sire(N) DUGONG (GUN DOG) *
18 t(I)p RENTE RTE around EN(d)
19 W(E)lsh CAMBRIC CAMBRIAN − (A + N) + C
20 f(R)esh TATES TASTE *
22 In(T)erior UTES (c)UTES(t)
24 r(I)ve TET TRIVET with E for RIVE
25 ho(S)e SULCAL (HOUSE CALLS) * = (SULCAL + HOSE) *
27 (T)ides NEAPED NEED around (A + P)
28 Ma(D)ge OWL (l)OW-L(ife)
30 (E)ast LUDS LDS around U
33 nippe(R) ELROY (ELROY + UNIT) * = ROUTINELY *; ref. The Jetsons cartoon character
36 (H)urt ILL LUCK ILL + L + DUCK − D
37 p(E)ace CORNI CORNISH − SH
38 cha(R)ged NAPIER RAN < around (PI + E)
39 Conve(R)t INGESTA (EATING + S) *
40 sava(G)e UNTAME ((GENU − G) around MAT) <
41 F(O)rmer ETEN EATEN − A
42 marke(T) SKILL-LESS SKI + ’S after (SELL + L) <
43 (T)aunt SCHMOCK MOCK after SCH
Down
1 v(A)ntage AVANT (VANTAGE − G(rap)E) *
2 (B)ust CANTICUMS (MUSIC CAN’T) *
3 p(E)rt NITRE (p)ERT IN(tangible) <
4 bea(R) ATTESTED RAT − R + SET < + TED
5 (B)e LEONIE EON in LIE
7 fo(O)t HEDER HEDER(a)
8 vote(S) LOGROLL LOG + ROLL
9 (H)ip KININ IN after KIN
10 b(A)rd’s ENGAOLS (GLEANS + O) *
12 (F)og STEAM UP S + TEAM UP
13 No(T)ice ENTOZOIC NOTICE * around OZ
17 d(I)m OBSCUREST (C(o)O(k)E(r)S + BURST) *
21 (S)ated FULL-LENGTH FULL + L + ENG + TH(e)
22 ou(T) UNCINUS UNCTUOUS with IN for OUT <
23 routin(E) SPECIAL SPECI(e) + A + L
26 (R)eckoned ACCOMPTED ED after COMPACT *
29 Sha(N)E WARNED WARNE + ’D
31 Unf(I)lled BLANK BLACK with (conservatio)N for C(onservation)