A.T. Robertson Commentary 1 Timothy 1:19

"holding faith and a good conscience; which some having thrust from them made shipwreck concerning the faith:" — 1 Timothy 1:19 (ASV)

Holding faith and a good conscience (εχων πιστιν κα αγαθην συνειδησιν). Possibly as a shield (Ephesians 6:16) or at any rate possessing (Romans 2:20) faith as trust and a good conscience. A leader expects them of his followers and must show them himself.

Having thrust from them (απωσαμενο). First aorist indirect middle participle of απωθεω, to push away from one. Old verb (see Ro 11:1f.).

Made shipwreck (εναυαγησαν). First aorist active indicative of ναυαγεω, old verb from ναυαγος (shipwrecked, ναυς, ship, αγνυμ, to break), to break a ship to pieces. In N.T. only here and 2 Corinthians 11:25.

Concerning the faith (περ την πιστιν). Rather, "concerning their faith" (the article here used as a possessive pronoun, a common Greek idiom).