Christians are not under the Mosaic Covenant. If they choose to dabble with Moses they bring a curse upon themselves as it is effectively rejection of the New Covenant.
A woman can not have two husbands.
1 Or do you not know, brethren (for I speak to those who know the law), that the law has dominion over a man as long as he lives?
2 For the woman who has a husband is bound by the law to her husband as long as he lives. But if the husband dies, she is released from the law of her husband.
3 So then if, while her husband lives, she marries another man, she will be called an adulteress; but if her husband dies, she is free from that law, so that she is no adulteress, though she has married another man.
4 Therefore, my brethren, you also have become dead to the law through the body of Christ, that you may be married to another— to Him who was raised from the dead, that we should bear fruit to God.
5 For when we were in the flesh, the sinful passions which were aroused by the law were at work in our members to bear fruit to death.
6 But now we have been delivered from the law, having died to what we were held by, so that we should serve in the newness of the Spirit and not in the oldness of the letter.
Romans 7:1-6
The net effect of tithing (The Mosaic Law) is barrenness and blindness. Remember - its all or nothing. You cant take one of the 613 Laws of Moses and skip the rest. If you reject Christ The Law of the Spirit of Life in Christ Jesus) and cling to the Law of Moses you must make sure to keep it 100% form your birth to your death.
9 You are cursed with a curse, For you have robbed Me, Even this whole nation.
10 Bring all the tithes into the storehouse, That there may be food in My house, And try Me now in this,” Says the Lord of hosts, “If I will not open for you the windows of heaven And pour out for you such blessing That there will not be room enough to receive it.
Malachi 3:9-10
10 For as many as are of the works of the law are under the curse; for it is written, “Cursed is everyone who does not continue in all things which are written in the book of the law, to do them.”
Galatians 3:10
15 But even to this day, when Moses is read, a veil lies on their heart.
16 Nevertheless when one turns to the Lord, the veil is taken away.
17 Now the Lord is the Spirit; and where the Spirit of the Lord is, there is liberty.
18 But we all, with unveiled face, beholding as in a mirror the glory of the Lord, are being transformed into the same image from glory to glory, just as by the Spirit of the Lord.
2 Corinthians 3:15-18