Eleven years ago I had a stroke. Physical and occupational therapy was rough on me. I had to learn everything from ground zero. Occupational therapy taught me how to dress, put on my shoes, brush my teeth, comb my hair etc.
On thing for certain, before my stroke I did not do it right! When I dressed myself with my pants, I would slip them on with ease. But after my stroke I had to do it right - put on the pants.
The difference in slipping into a pair of pants and putting a pair of pants on is as different as night from day. To slip on is to not take any thought what you are doing. I notice this with my good leg. I do not have to pay attention because it moves and the leg of the pant goes on with east. But, when it comes to putting on my pant leg with my bad leg, I have to take deliberate thought with much care so that it will come out all right.
This reminds me of the verses in Ephesians 4:22-25 - "That ye put off (not slip off) concerning the former conversation (behavior) the old man, which is corrupt according to the deceitful lusts: And be renewed in the spirit of your mind; And that ye put on (not slip on) the new man, which after God is created in righteousness and true holiness. Wherefore putting away lying, speak every man truth with his neighbor: for we are members one of another."
God expects us to take the effort to put on the Lord Jesus Christ. He doesn't want us to slip Him on haphazardly. He wants us to take some thought! May God help us.