Don't know who you "debated", but it definitely wasn't someone of the church of Christ, nor are coC ministers that stupid or scripturally ignorant.
The coC doesn't believe in nor preach tithing as it's not a requirement of the NT. The bible does not define an amount or percentage but rather as you purpose in your heart.
2 Cor 9:7
"Every man according as he purposeth in his heart,
so let him give; not grudgingly, or of necessity: for God loveth a cheerful giver."
Also, the coC does NOT regard the Sabbath in any way as Holy or special, nor any day for that matter, nor does it gather together as the body of Christ to worship on the Sabbath; but rather, the church gathers together as the body of Christ according to scripture, on the first day of the week, Sunday.
Acts 20:7
"
7And upon the first
day of the week, when the disciples came together to break bread, Paul preached unto them, ready to depart on the morrow; and continued his speech until midnight."