Gentiles are not bound to Jewish laws, for they are not Jews, yet Christians have to be of the spirit and depart from the flesh. Therefore, in Christianity, Fornication is done with married or engaged persons by singles: both the engaged and singles are fornicators.
Married persons playing with anyone other than their spouses commit Adultery.
Here Christians face the most challenging of all the Gospel: ‘Fornicators shall not inherit the kingdom of heaven’. ‘Deny thy self and follow me’. Thus gentiles are called to repent and baptize.
A Christian marriage is defined by a promise of fidelity between spouses before God in heaven and a number of witnesses on earth, to take each other as husband and wife until death do them part. No church priest/minister is required for this, simply a number of people, sincere prayers, then the promise/marriage. This is all God requires from you. The witnesses will also sign a document as proof to the world that this ceremony taking place.
You may now also legally bind the wedding by going through the required governmental procedures to make this marriage legally binding on earth as, unfortunately, governments do not acknowledge any such marriage as described above, only God does.
Even before you get married and baptize, you must understand the commandment on ‘Adultery‘. For Christ further teaches us that whoever puts away his wife ( and logically vise-versa also ) save it be for fornication(translation error) this should be ‘adultery’ as one can’t commit fornication once married; only ‘adultery’ forces her to commit adultery, and also himself commits adultery.
If your partner dies, you are free to re-marry and are not in adultery if you do so. If as it was for the Jews, so it is for Christians, then so it is. Remember, if one Jewish law applies to Christians then all Jewish laws apply to Christian and thus also ‘circumcision’.
From the Holy Ghost, Through Apostle Paul, to the JEWS:
CO1 7: 2 Nevertheless, to avoid fornication, let every man have his own wife, and let every woman have her own husband.
TH1 4: 3 For this is the will of God, even your sanctification, that ye should abstain from fornication:
TH1 4: 4 That every one of you should know how to possess his vessel in sanctification and honour;
TH1 4: 5 Not in the lust of concupiscence, even as the Gentiles which know not God:
TH1 4: 6 That no man go beyond and defraud his brother in any matter: because that the Lord is the avenger of all such, as we also have forewarned you and testified.
TH1 4: 7 For God hath not called us unto uncleanness, but unto holiness.
You remember these sayings of Christ’s:
MAT 22: 14 Many are called but few are chosen.
MAT 7: 21 Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven.
MAT 7: 22 Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works?
MAT 7: 23 And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.
MAT 7: 24 Therefore whosoever heareth these sayings of mine, and doeth them, I will liken him unto a wise man, which built his house upon a rock:
MAT 7: 25 And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock.