What is all required for a Christian marriage ceremony? How much of what we do is purely tradition? Of course, there are the legal requirements of a marriage certificate, an officiator and witnesses, but what are the Biblical requirements for a marriage to be "official"?
The Westminster Confession of Faith says, "It is lawful for all sorts of people to marry, who are able with judgment to give their consent." (WCF Ch.24). This means that marriage is an institution given by God to all mankind. Does a wedding have to be Christian to be lawful in the eyes of God? No. A civil magistrate or even a sea captain in international waters administers legal marriages. In fact, any jurisdictional authority that society recognizes as such can invoke a covenant of marriage in that society. That's why Communist nations have marriage as well as theocratic Muslim. Marriage is a creation ordinance meant to be enjoyed by all when administered by a recognized body. All marriages are lawful in the eyes of God, so long as they conform to His Word. Most marriages today are state marriages. In fact, if you read our form, the title is the Form for the Confirmation of Marriage before the Church. That's because the civil magistrate did the actual legal marriage day/s before. Our form confirms what has already transpired in the court. It's all legal and binding. They only hoped and prayed that the two newlyweds would restrain themselves before the marriage was confirmed in the Church!
So, does a marriage have to be Christian? Not if you are not a Christian. If you are, then you most certainly want the blessing of God upon your marriage and future. You desire to deeply involve the Lord in the most serious of your earthly relationships. You would wish God and man to bare testimony to your faithful covenant vow. Surely you want God's blessing. If so, then 1 Corinthians 14 comes into view. If you are going to do something involving the LORD, and His Church, then "Let all things be done decently and in order." That means having a plan that glorifies God. And if you invite the King of Kings to bless your nuptials (and I'll admit, many only do it out of superstition, as their ensuing reception will prove), then have a particular eye on His presence as you do. To that end, the Reformed Churches have distilled for us what decorum and good order look like, using the Bible as their framework. Yes, other Christian churches do it differently. But we operate within the confines of what we believe pleases the Lord. This includes two people who want to get married, a few witnesses, and a lawful minister who conducts the marriage ceremony. He reads the Word, the Form, prays with and for the couple, and then gives a scriptural charge for their new life together. That's it. It meets the criteria of 1 Cor 14 and takes into account that the Lord of Glory is present. You might include singing a Psalm, or suchlike, or have a processional and recessional. But it does not need to be elaborate, is what I am saying. I have done an FRC wedding out west where it was just the bride and groom, one flower girl, and both sets of parents. And it was not a Covid wedding either (2011). It was just simple. Simple but godly.
So what is required? A legal piece of paper and two willing adults. A "Christian wedding," as you call it, calls for Christian things. I hope this helps.