Yes biggie!

Two things on this item, the subject of "train them remembering continually the power of sin."

1.  "Children require no schooling to learn to sin."

It is the easiest thing in the world to sin.  And while we are not to put stumbling blocks in our children's way, we should also be mindful of their potential as we discipline them.   We need to get away from taking offense at our children's behavior, like they are just trying to drive us crazy.  It's actually much worse than that!  They are born at enmity with God!  (Romans 8:7)  We have a common enemy, who seeks to steal, kill and destroy.  (John 10:10)  As we discipline our children, it is best to point them to the cross, God's solution for dealing with sin for the unsaved, and the source of our power to win over sin for the saved.  

2.  "Never listen to those who tell you your children are good..."  

Ug.  Today, this would be akin to the people who say, "Well, at least they are not on drugs..."  as you are dealing with something "not so bad," like name-calling or hitting or not doing their chores.  The world allows for and expects a certain amount of disobedience in a child....and so should we.  But the response that God expects by parents is vastly different than the world's idea.  The world will say, "Oh, its no big deal..."  God says, "A man reaps what he sows."

Say you are teaching a child to say "excuse me" to folks in the store when they block someone's path.  You are at Walmart, and they have a violation, and you stop to have them say "excuse me".  You give the child their cue, and they get ready to do their thing, but the object of the "excuse me", sensing the child's hesitance, interrupts and says "No problem, they are fine." 

Or, once, one of our kids was having an attitude about bread crusts.  We had been working with them for probably weeks, I don't know.  One day we had sandwiches, and after everyone had eaten, one had left their crusts.  By now, it was after lunch.  I sat at  the table with the child and encouraged him as he slowly finished it, and praised him for each bite.  We were getting somewhere!  It was actually peaceful.  We took a bathroom break and came back to find the plate was gone!  A visiting extended relative had thrown the small remaining bit in the trash before we could have our victory celebration.  They had been watching the exchange while doing dishes, and may have decided it had continued long enough!

No biggie!

To the world, having our child say "excuse me" or having them finish their crusts seem so miniscule, but for parents, we may see these things as little steps to obedience in bigger areas, in fact, as the foundation to obedience in all areas, as the Bible says, "Children, obey your parents in all things, for this is well pleasing unto the Lord."  Col. 3:20

No christian family should be an island, but it is often difficult in public settings to follow through with how the Lord would have us discipline when many around us tell us how "wonderfully behaved" our children are, or how "it's okay, they aren't in the way" or "that's okay, they are fine" when we try to correct disobedience.  

Many people are so used to seeing undisciplined children...children whom the Lord dearly loves, but who go without nearly any consistent discipline.  These often unloved (Proverbs 13:23), neglected children do grow up and get on drugs, and people see them on the news!  In comparison, our little path-blocker, or crust-scorner, is a saint!    

Loving, discerning parents see their children's faults and weaknesses, and out of LOVE, attempt to diligently address them.  We want to do things God's way, and he disciplines those he loves.  (Heb 12:6)  And this can come across as extreme to many in the world, who think that part of a "healthy" childhood is a little bit of secret fun, tricks, practical jokes, folly, and the like.  

The root of this problem is that the world minimizes the problem of sin.  And of course, the world balks at the idea of the need for a sacrifice for sins, trivializing what Jesus did for us on the cross. 

Even the righteousness of God 

which is by faith of Jesus Christ 

unto all and upon all them that believe: 

for there is no difference: 

For all have sinned, and come short of the glory of God; 

Being justified freely by his grace 

through the redemption that is in Christ Jesus: 

Whom God hath set forth to be a propitiation 

through faith in his blood, 

to declare his righteousness 

for the remission of sins that are past, 

through the forbearance of God; 

To declare, I say, at this time his righteousness: 

that he might be just, 

and the justifier of him which believeth in Jesus.  

Romans 3:22-26