Mat 18:7 Woe unto the world because of offences! for it must needs be that offences come; but woe to that man by whom the offence cometh! (KJV)
Mat 18:5 And whoso shall receive one such little child in my name receiveth me.
Mat 18:6 But whoso shall offend one of these little ones which believe in me, it were better for him that a millstone were hanged about his neck, and that he were drowned in the depth of the sea.
Mat 18:7 Woe unto the world because of offences! for it must needs be that offences come; but woe to that man by whom the offence cometh!
Mat 18:8 Wherefore if thy hand or thy foot offend thee, cut them off, and cast them from thee: it is better for thee to enter into life halt or maimed, rather than having two hands or two feet to be cast into everlasting fire.
Mat 18:9 And if thine eye offend thee, pluck it out, and cast it from thee: it is better for thee to enter into life with one eye, rather than having two eyes to be cast into hell fire.
Consulting the context, it appears to me that the warning Jesus gave against offending and not receiving a child is related to not receiving Jesus Himself.
Causing a child to go astray by teaching them falsehood is an offence that places the person who caused the child or the believer in Christ to lose his or her faith in Christ subjects the offender to the penalty of everlasting hell, to be cast into hell fire.
There are some today who attempt to explain away what Jesus taught about everlasting or eternal punishment. I think that to lessen this severe warning of Jesus is to make a person subject to the very punishment Jesus threatened.