Do We Still Have To Define Marriage The Way God Does?

Marriage and sexuality are not only personal issues but important to each of us. The questions of today are: Can we define marriage as we want to, or is it something God defines for all times and all societies? And if God has said what marriage is, then can we change it? Is He right? Who has the authority to decide? What will we do with what God's Word has said? If someone disagrees with us and God's Word, can we still be friends?
So many questions for us as a church in these challenging times.