Date issue with formatting to standard of report

I have one column that is string but it is actually a date in this format YYYYMMDD and time as well. A typical date would be:

2017-07-01 05:53:07.100 -04:00

All my other dates on the row are mmddyy.

I tried this formula it does compile but is failing in runtime 'Bad date format string'

cDate(ToText(cDate({H1bac_2017_.RESULT_COMPLETIONDATE}),"MMddYYYY"))