According to the page, you should recite Ephesians 6:10-18 before going to bed in them:
6:10 Finally, my brethren, be strong in the Lord, and in the power of his might.
6:11 Put on the whole armour of God, that ye may be able to stand against the wiles of the devil.
6:12 For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.
6:13 Wherefore take unto you the whole armour of God, that ye may be able to withstand in the evil day, and having done all, to stand.
6:14 Stand therefore, having your loins girt about with truth, and having on the breastplate of righteousness;
6:15 And your feet shod with the preparation of the gospel of peace;
6:16 Above all, taking the shield of faith, wherewith ye shall be able to quench all the fiery darts of the wicked.
6:17 And take the helmet of salvation, and the sword of the Spirit, which is the word of God:
6:18 Praying always with all prayer and supplication in the Spirit, and watching thereunto with all perseverance and supplication for all saints;
So it's not just a Klan robe, it's a Klan robe that can resist the wiles of the devil and quench the fiery darts of the wicked! Man, I really feel sorry for any kid whose mom gets him these pajamas.

"Mommy, mommy, I had a accident in my loins as they were girting about with the truth of the Lord!"