Thank you for your reply, I tried the code but unfortunately it hasn't worked for me. However, the following code has worked:
Dim Z As Long, Position As Long, Words As Variant, Cell As Range
Words = Range("content_check")
For Each Cell In Sheets("A+_Creation").Range("G13,G15,G19,G21,E30:E6000")
If Len(Cell.Value) Then
For Z = 1 To UBound(Words)
Position = InStr(1, Cell.Value, Words(Z, 1), vbTextCompare)
Do While Position
Cell.Characters(Position, Len(Words(Z, 1))).Font.ColorIndex = 3 'Red
Position = InStr(Position + 1, Cell.Value, Words(Z, 1), vbTextCompare)
This was made by Rick Rothstein at mrexcel.com, so all credit should go to him.
Thank you very much for your help though!