Treatment of children is the key to EVERYTHING important.

EDIT: How does one build strong children? Not by offending them or being harsh with them; children grow strong when given freedom (as every living thing wants, by definition) within the framework of respecting the rights of others.

Matthew: 
18:1 At the same time came the disciples unto Jesus, saying, Who is the greatest in the kingdom of heaven? 


18:2 And Jesus called a little child unto him, and set him in the midst of them,

18:3 And said, Verily I say unto you, Except ye be converted, and become as little children, ye shall not enter into the kingdom of heaven. 


18:4 Whosoever therefore shall humble himself as this little child, 
the same is greatest in the kingdom of heaven. 


18:5 And whoso shall receive one such little child in my name receiveth me. 


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.

Mark: 
10:13: And they brought young children to him, that he should touch them: and his disciples rebuked those that brought them. 


10:14: But when Jesus saw it, he was much displeased, and said unto them, Suffer the little children to come unto me, and forbid them not: for of such is the kingdom of God. 


10:15: Verily I say unto you, Whosoever shall not receive the kingdom of God as a little child, he shall not enter therein.