This is a call and ecouragement to Trust God and not let go
The " he hath denied the faith" is the key.Lack of Faith is the reason he is not providing for his house hold. God looks after his children and in the same manner we as believers are to throw our selves onto Gods promise to provide for us even if its work.
If there is no work especially now, and God will provide with "Hidden Manna"
Re:2:17: He that hath an ear, let him hear what the Spirit saith unto the churches; To him that overcometh will I give to eat of the hidden manna, and will give him a white stone, and in the stone a new name written, which no man knoweth saving he that receiveth it.
Infidel means "apistos" ......unfaithful, faithless,not to be trusted, perfidious.