What would I do if Christ did not uphold me?

I would fall.

"It is not fit that, in a covenant of mercy and saving grace, the reward of life should be suspended on man's perseverance, as depending on the strength and steadfastness of his own will. It is a covenant of works, and not a covenant of grace, that suspends eternal life on that which is the fruit of a mans own strength, to keep him from falling. If all is of free and sovereign grace, then free grace has undertaken the matter to complete and finish it, and has not left it to men themselves, and to the power of their own wills, as it was under the first covenant. As divine grace has commenced the work, it will finish it; and therefore we shall be kept to the end."
Jonathan Edwards, Charity and Its Fruits (emphasis mine)

As some of you know, I've spent the majority of my life professing to be a Christian. Then I got saved, shortly before my forty-first birthday.

My relationship to the church all those years often brings to mind childhood memories of the felt boards my Sunday School teachers used to use. They would put up a cloth Jesus. Then they would put up a disciple or two. When the story changed, those flimsy felt disciples would be peeled away to make room for the next character. I, throughout my life, like a felt disciple, adhered myself from time to time, as the story suited me, to the church and its Savior. If I felt a need. I would be there. If I wanted some freedom to be myself - live my own life - I pulled away. This I did time and time again, as did most of the "disciples" I'd known. I sometimes wondered about those occasional disciples that didn't seem to be separate pieces of felt. The ones that stayed up on the board and were never removed - the ones whose lives were bound up with the Savior on the board. Though made of the same stuff, they were different. They were permanent. I wondered about them, but couldn't imagine living that way. I liked my freedom.

As I said, something happened to change all that when I was forty. My life was turned upside down. What I had thought of as freedom, I was beginning to see, was no freedom at all. I was a slave to the various pullings and tuggings of my conflicting desires and appetites. I was a little scrap of fabric, demanding my freedom yet being blown about, trampled and useless. And one day I recognized what I was, and what my "freedom" had done for me. I ran back to the board, as I'd often done. I needed help. But this time I looked at that Savior and realized something new. He is beautiful. I didn't just want something from Him. I wanted to be with Him, forever. I didn't just need some help. I needed to be changed. I wanted to be changed. I wanted to be one of the permanent ones - more than anything in my life, I wanted to be one of the disciples who could never be pulled away from the presence of that Savior. It became the driving force in my life, my great goal. But how could I know that I would not be peeled away this time?
I'd never been able to hang on before (or even really wanted to). What hope did I have that I could hold fast to the end and be saved? I asked whoever would listen, until I finally met a pastor who introduced me to the Scriptural teaching of "the perseverance of the saints". That question is the reason the "Doctrines of Grace" have become so dear to me. I do not love doctrine for doctrine's sake - as some are inclined to do. I love it for the hope it gives me that I can persevere to the end and be numbered among those who are faithful unto death and receive the crown of life. (Rev. 2:10)