Comma Splice

My earlier posting touches, among other things, on two distinct sentences/statements linked by a simple comma (comma splice).
Such weakness appears to be plaguing many writers including experienced ones and editors.
Below are examples taken from newspapers:-
1) His body was covered with tattoos, many of them had religious themes. (This sentence needs to be separated into two sentences: His body was covered with tattoos. Many of them had religious themes.)
2) I have several friends who have had cancer, some have passed away while others have survived. (Similarly this sentence needs to be separated into two sentences: I have several friends who have had cancer. Some have passed away while others have survived.)
The amended sentences should, beyond dispute, be grammatically correct and conveying the meanings intended.