Cornelius a Lapide interprets this verse as, He that finds his life (ψυχὴν), which is, "the corporeal safety of life, when in peril of death, through denial of the faith", that such a person will lose his soul (ψυχὴν), i.e., the eternal salvation of his soul.
According to Cornelius a Lapide's interpretation, this passage suggests that someone who finds physical safety (existence) through denying their faith will ultimately lose their spiritual well-being (spirit).