I was never very good at math but I am sure that one plus one equals two.
However, in God's marital math it is not the case. According to His factoring the proper answer is one plus one should equal one.
From the beginning when God created Eve to be a helpmate for Adam, it was the purpose of God for man and wife to enjoy the same unity of spirit that is enjoyed by the Trinity where Father plus Son plus Holy Spirit equal one.
So, how can this happen?
Become one in purpose.
If a husband and wife are to get the math right in their marriage they cannot disagree on the purpose for their marriage and their lives. God called them to Himself and then He called them together to enjoy Him as a couple. The purpose of a Godly marriage is to worship, serve and honor God better as a couple than either could individually. Are you and your partner united around His purpose?
Become one in priorities.
In order to serve God in unity, a couple must share the same priorities. Priorities are the ordering of your values - what is most important to you. You will make your decisions according to your priorities and if you have differing priorities how can you agree? Actually, this is an important consideration prior to marriage. That is a conversation that should be had often during the courting days. The Bible says, "How can two walk together except they agree?" Priorities and purpose are two of the most basic levels of agreement. And, if you share a central purpose your priorities are more likely to agree.
Become one in passion.
Passions are powewrful. Passions arise from an intense positive feeling toward something or someone. Passions determine where your heart and mind will be aimed. Here is a fact about passions, they are so powerful that if you don't control them they will control you! They are so strong that if a married couple do not share the same passions their hearts and minds will drift apart. The consuming passion for any godly marriage must be knowing God, obeying God and serving God. God's Word must fuel the passions of a married couple. A shared passion for God is the strongest glue a marriage can have. Become united in your spiritual passion and your passion for one another will go to a new level.
Become one in perspective.
A final area of agreement should be beliefs. For two to become one they must share the same essential beliefs about God, about the Bible, about church doctrine, and about how those beliefs are expressed in attitudes and actions. In I Corinthians 7, Paul talks about the importance of being united with a believer and prohibits being "yoked with unbelievers". Again, these are conversations that should happen during the courting and dating process. You should not enter a relationship as intimate as marriage thinking you can compromise with your partner's differing beliefs or even worse, planning to change their beliefs. Differing core beliefs should be a deal-breaker.
Unity in marriage is God's design for a couple in order to share in their joy and multiply their joy. You will have a great chance of realizing that goal if you share a common purpose, common priorities, common passion, and common perspectives.
If these important factors don't add up in a marriage, there will be subtraction happening in the relationship that could eventually result in a painful division.