From the beginning God commanded that His people only marry believers.
Most problems Israel had were due to false gods and marrying pagan worshippers.
In the New Testament we were are warned to 'not be unequally yoked with unbelievers.
So, it is obvious Christians may marry anyone 'in the Lord', meaning fellow Christians.
There may be a few obstacles in such a marriage but it won't be with the Lord but with those who don't know the Scriptures or love the Lord.