Matthew 18:19-20 GNT
“And I tell you more: whenever two of you on earth agree about anything you pray for, it will be done for you by my Father in heaven.  For where two or three come together in my name, I am there with them.”
God designed marriage to be an almost infinitely powerful union. Tragically, many married people will never even learn of the incredible potential of their marriage much less realize it.
The kernel of God’s idea regarding marriage is “…and the two will become one.” (Matthew 19:5 GNT). In this simple yet profound truth resides potency only surpassed by God’s omnipotence.
As we go through scripture, we find that oneness (of purpose) is an indomitable force. At Babel for example, when God came down and saw the oneness of language (purpose) of the people trying to build the first skyscraper, God said…
… Behold, they are one people and they have all one language; and this is only the beginning of what they will do, and now nothing they have imagined they can do will be impossible for them. (Gen 11:5-6 AMP)
It is the same spectre of possibility that is referenced when Jesus says “whenever two of you on earth agree about anything you pray for, it will be done for you by my Father in heaven.”
Why then do we not see married couples live victorious lives of answered prayers? Two possible answers come to mind. First, it is that many do not even know this truth, and secondly, being married does not automatically help a couple meet the requirements, because being married does not always equate oneness or agreement.
In fact, many couples are only so in name. The only evidence of their marriage is the piece of paper they were handed at their wedding, and perhaps the children they have had. Not only do they not have any oneness of purpose, they are in fact generally at variance. For such a couple, scripture indicates that rather than being undeniable, their prayers are instead ineffective.
In the same way you married men should live considerately with your wives, with an intelligent recognition of the marriage relation, honoring the woman as physically the weaker, but realizing that you are joint heirs of the grace (God’s unmerited favor) of life, in order that your prayers may not be hindered and cut off. Otherwise you cannot pray effectively. (1 Peter 3:7 AMP)
By God’s design, two people ought to get a better reward for their labour (Eccl 4:9). The caveat however is that a better reward is only promised for joint labour. Just as they are joint heirs, whereby neither can gain access to their share of the inheritance without the other (1 Pet 3:7), labouring alone never yields the full potential.
Once ever we realize the secret of oneness of purpose in marriage, we will unlock, and unleash a power so potent that nothing shall be impossible to us.