According to 2 Cor 6:14, the Bible doesn’t allow believers to be unequally yoked with non believers (Marriage)? Is it then a sin or also not allowable for a pastor to marry the two should they insist? Or is marriage on it’s own only applicable or was established for believers only?
I don’t think the Bible says it’s a sin for a believer to be married to a non-believer. As a general rule Paul strongly urged believers not to be involved in any kind of relationship with unbelievers because we have nothing in common with them, and our differences will either cause strife in the relationship or compromise in the believer’s walk with the Lord.
Both secular and Christian marriage counselors advise their clients not to knowingly take anything into a marriage that could threaten its stability down the road. I know some pastors who won’t marry a believer to a non-believer because of this. But I don’t know of any who would consider it a sin to do so.