The heart shows our intentions. Surely if we want to steal and would if we thought we could get away with it, that's a problem with the heart. Lusting in the heart is also a sin if the intention is there but remains unexpressed.
You did not respond to other points -- like Jesus being tempted in all things. That tells me that thoughts crossed his mind but he never entertained them in his heart.
Again you failed to address one of my points. Genesis speaks about wanting to be "wise." It's one of the first lessons in the Book.
Genesis 3:6 And when the woman saw that the tree was good for food, and that it was pleasant to the eyes, and a tree to be desired to make one wise, she took of the fruit thereof, and did eat, and gave also unto her husband with her; and he did eat.
Charity is surely the principal thing.
Colossians 3:12 Put on therefore, as the elect of God, holy and beloved, bowels of mercies, kindness, humbleness of mind, meekness, longsuffering;
13 Forbearing one another, and forgiving one another, if any man have a quarrel against any: even as Christ forgave you, so also do ye.
14 And above all these things put on charity, which is the bond of perfectness.
1 Corinthians 13:2 And though I have the gift of prophecy, and understand all mysteries, and all knowledge; and though I have all faith, so that I could remove mountains, and have not charity, I am nothing.
Well, I'm not really disagreeing with you, outside of 'correcting' you on your contention with my remark about wisdom. So I won't address your points, because they're valid in a sense, ...but they don't undermine my point.
Wisdom is the greatest gift, and that is by God's design. You keep comparing intellect or wordly knowledge, against it. They are not the same.
Knowing that something is a sin, as in the knowledge that Adam & Eve gained, is very different than knowing
why it's a sin. This was my point on how to desist sin, if one understood the abhorrent nature of it, and why the interdiction, it would make most people repulse, not feel compelled.
Jesus was tempted, it does not mean that he entertained or fantasized about the sin. Wisdom protected him, he knew that the glory or pleasure that sin offered, was only fleeting, basal and incomparable to what God offered. Thoughts are sinful when one desires the sin, not simply meditating on its vice, or on just the fact that it exists. We can talk about what constitutes a sin, without sinning, for example.
I liked your idea about when temptation creeps in, to divert the thought by doing the opposite i.e. showing affection to your wife, working hard, doing charity, or doing any act that is contrary to the thought.
But, wisdom is still better, because it's not contingent upon a subsequent action to be successful. It doesn't feel threatened in the first place, it sees the ugliness and danger right away.