Craftiness is the attitude of being cunning, shrewd, sly, subtle or surreptitious (secret, sneaking, underhand, clandestine). The crafty is ingenious in deception, giving a false impression of his real intent.
Craftiness was the first stealth weapon employed by Satan against mankind, which indeed was devastating (cons. Gen.3:1-7, 22-24). After the fall, some men did deploy it to attain some temporary goal, but not without consequence (Gen.27:16-23, Jos.9:4-15, Matt.26:4,47-50, Lk.20:19-23).
Craftiness sometimes manifests as dissimulation ie hiding under a false appearance (cons. Lk.20:20-23, Acts 23:12-16), deceptive speech or actions (cons. Ps.36:3, Prov.12:5, 27:6, Lk.22:47-48), dishonesty in business (cons. Deut.25:13, Prov.11:1; Mic.6:11; Prov. 21:6).
In the Church, the possessors of this ungodly trait with or without any condemnation of their conscience, get involved in inglorious activities like ostentatiously using gifts to bribe/pave their ways into the hearts of people with the intent of securing some position, unmerited favour, or life partner (as detailed last week)(cp. Matt.6:3).
A child of God is expected to be sincere, honest and child-likely simple in heart (Tit.2:7, Phil.1:9-10; 1Cor.14:20, Lk.18:17).