6 but whoever should cause one of these little ones who believe into me‘Into’ not ‘in’. The Lord Jesus always said "believe into [Greek εις] Me", never "believe in [Greek εν] Me". (In John 3:15 a very few Greek manuscripts of inferior quality have "in", against 99.5% that have "into".) People believe in Santa Claus, the Easter bunny, the goodness of man, or whatever, but it does not change their lives. Similarly there are many who say they believe in Jesus, but it makes no difference in their lives. You have to believe into Him—commitment and identification are involved—it is a move from being outside to being inside. to fall, it would be better for him if a large millstone were hung on his neck and he were drowned in the depth of the sea!It is preferable to suffer an ignominious physical death than to destroy the faith of a child who believes into Jesus. What is worse than an ignominious physical death? Spiritual death—in verses 8-9 Jesus refers overtly to hell fire. If you send a child to hell, you go too! What about all the teachers who have dedicated themselves to destroying the faith of their students?
God loves children
10 "See to it that you do not despise one of these little ones, for I say to you that in heaven their angels always see the face of my Father, who is in the heavens."These little ones" refers to the literal children who were in the room. In verse 2 Jesus called one over, so it was obviously in the room, but the playmates would naturally stop to see what was going to happen, so there were several in the room. This verse suggests the existence of guardian angels.