"God is the strength of my heart" is known to be difficult.
The most difficult part is where there are too many chords filled up in the part of "주를 의지하리~" If you take a look at the 3-4 bars, All the chords except for Bm7 are pulled when proceeding Bm7 - A/C# - D-D/E. I marked this part in the video so you might want to focus on practicing this part separately. You should get your fingers more used to it part than thinking.
You should get your fingers used to it first and remember all the chords except for Bm7 should be pulled. Another difficulty is that once you start and sing, an introducer might get confused with timing to get in. I tried my best to make the song to start smoothly, but you should try to arrange and personalize while playing it.
In the case of transformation,
1. You might want to omit 5-6 bars
2. You might want to repeat 5-6 bards over again instead of 7-8 bars
3. You might want to omit 5-7 bars
And there are a lot more options you can choose regarding transformation.
I am just giving you a guidance for the reference so refer to my guidance for your church.