How do you convince a goat that they are a goat?

I don't try. I simply preach and try to live the gospel message and let it convict who it will.

By leaving him alone...........

Everyone has consealed in themeselves to a degree to know right from wrong.

Some know they are goats and it's their job to convince you they are a sheep.

But the way of a fool is right in his own eyes....

Matthew 15:14

LET THEM ALONE: they be blind leaders of the blind. And if the blind lead the blind, both shall fall into the ditch.

Titus 3:10

A man that is an heretick after the first and second admonition reject

Well since you are talking spiritually speaking, they won't get convinced unless God has prepared their hearts or unless they are in some desperate circumstance. Could be they knew all along but wouldn't admit it to themselves unless they were desperate. Sometimes I wonder how many will call out to God when they see themselves dying and falling into the pit. I know a few have come back to life that way and committed themselves to the Lord but most of the time we know it doesn't happen.