Could you explain why Moses gave the certificate of divorce? What I mean to say is when was it that God's people were required to leave their non-Jewish spouses? What were the reasons for this? I am looking to use it for an example of commitment and covenants, such as marriage. Even if you have kids and have been married for years, God still requires what is right.
Where I am the big thing is what is the situation and the excuse that God doesn't speak clearly on it. I have heard people say this, so I need to clarify with an example in the Bible. I can use just the divorce laws in the New Testament, but this would help more.
The argument that God wasn't clear is an interesting one. Whether the person realizes it or not, at its roots the argument is that God was unable to express His Will clearly enough for men to follow, thus men can choose any way they want. If there is an objection, then the people blame God for not doing a good enough job of expressing Himself. "Surely you have things turned around! Shall the potter be esteemed as the clay; For shall the thing made say of him who made it, 'He did not make me'? Or shall the thing formed say of him who formed it, 'He has no understanding'" (Isaiah 29:16).
Obviously, this cannot be. God created our entire universe and not one of us or all of us combined understand what He has done. The idea that God is unable to communicate clearly with His own creation is ridiculous. "All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness, that the man of God may be complete, thoroughly equipped for every good work" (II Timothy 3:16-17).
Jesus states why the certificate of divorce was given. "They said to Him, 'Why then did Moses command to give a certificate of divorce, and to put her away?' He said to them, 'Moses, because of the hardness of your hearts, permitted you to divorce your wives, but from the beginning it was not so'" (Matthew 19:7-8). Divorce was not a part of God's plan for mankind. It was regulated because of people's stubbornness. I take that to mean that people often refused to work out their problems.
However, I think you are referring to a later time, during Nehemiah and Ezra's day. Here the problem was Israelites marry foreigners who did not become Israelites. The result were families whose children could not even speak the Israelite language of Hebrew and grew up familiar with idol worship. It was these spouses that Ezra and Nehemiah said had to be left. Take a look at the lesson "Mixed Marriages" for all the details. The article "They Promised to Put Away Their Wives" also deals with this event.