The following analogy has been stolen from Pastor Alistair Begg and expanded upon. I'm sure Alistair borrowed it as well, but I'll give him credit for it.
Imagine you are a young person and it's Christmas morning. You rush downstairs to find the tree surrounded by gifts and you search for the one with your name on it. You finally find it and begin to shake the box. You can't wait to unwrap it.
Your parents finally wake up, I mean it's 5:30 a.m. for goodness sake, and they tell you to wait just awhile before opening gifts. You are so excited to open that box.
Your parents finally get their coffee and Dad reads the Christmas story. Now, you can open your gift. You tear into the paper and discover what lies beneath, a remote control car! Dad gives you his pocket knife so you can open the box and pry apart all of the plastic pieces that tie down your long awaited prize. Once the car is free you set it down on the kitchen floor, you grab the remote and press down on the accelerator button and...
You look disheartened and try again.
You finally go back to the box to examine to see if you can figure out the problem.
BATTERIES NOT INCLUDED.
Right on the box in all caps those words every Christmas morning should be without: BATTERIES NOT INCLUDED. With those three words every promise the toy made you that morning was broken until tomorrow when a store opened up that had batteries.
Religion can be like this. Religion promises us a lot, but most promises are modified by a BATTERIES NOT INCLUDED clause. Religion gives us a great task, one that is worthwhile, but is unattainable because the batteries are missing. Religious people try and try but the power just isn't there.
Christianity is different.
Christianity is the only religion of BATTERIES INCLUDED. Christianity rests on the promise that for what we are to do God provides the power in which to do it. There are things the Christian will do after conversion, but he/she is supplied with the power to do it.
"His (Jesus') divine power has given us everything we need for life and godliness through our knowledge of Him who called us by His own glory and goodness. Through these He has given us His very great and precious promises, so that through them you may participate in the divine nature and escape the corruption in the world caused by evil desires.
For this very reason, make every effort to add to your faith goodness; and to goodness, knowledge; and to knowledge, self-control; and to self-control, perseverance; and to perseverance, godliness; and to godliness, brotherly kindness; and to brotherly kindness, love." 2 Peter 1:3-7
See, as a Christian you will grow. The remote control car will move, but it won't be from your own power. No, the car will move because of the batteries that were included. The power to follow Christ is not something we muster up, it is something that has been given to us and BECAUSE of that we make every effort to follow Him.
Religion gives us a task but no power to do it. Christianity gives us a task as well (not to earn salvation but to experience it) and gives us the power to do it.
More than that, at death the Christian won't need to wonder if he's done enough to gain the salvation of his soul. At death he knows that he will receive it, not because of what he's done, but entirely because of what Christ did.
If you are a Christian thank God that figuratively stamped on you are the words BATTERIES INCLUDED. If you are not a Christian, I ask you to stop trying to do the impossible task of powering yourself. Stop trying and rest in what Jesus has already done for you and get ready for what Jesus is going to do through you if you believe in Him today.