1 I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service.2 And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God. 3 For I say, through the grace given unto me, to every man that is among you, not to think of himself more highly than he ought to think; but to think soberly, according as God hath dealt to every man the measure of faith. 4 For as we have many members in one body, and all members have not the same office: 5 So we, being many, are one body in Christ, and every one members one of another. 6 Having then gifts differing according to the grace that is given to us, whether prophecy, let us prophesy according to the proportion of faith; 7 Or ministry, let us wait on our ministering: or he that teacheth, on teaching; 8 Or he that exhorteth, on exhortation: he that giveth, let him do it with simplicity; he that ruleth, with diligence; he that sheweth mercy, with cheerfulness. 9 Let love be without dissimulation. Abhor that which is evil; cleave to that which is good. 10 Be kindly affectioned one to another with brotherly love; in honour preferring one another; 11Not slothful in business; fervent in spirit; serving the Lord; 12 Rejoicing in hope; patient in tribulation; continuing instant in prayer;13 Distributing to the necessity of saints; given to hospitality. 14 Bless them which persecute you: bless, and curse not. 15 Rejoice with them that do rejoice, and weep with them that weep. 16 Be of the same mind one toward another. Mind not high things, but condescend to men of low estate. Be not wise in your own conceits. 17 Recompense to no man evil for evil. Provide things honest in the sight of all men. 18 If it be possible, as much as lieth in you, live peaceably with all men. 19 Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord. 20 Therefore if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire on his head. 21 Be not overcome of evil, but overcome evil with good.
Relationships are tricky so I have learned to use “Romans 12” in all of my dealings. It really does not matter if the person that I am dealing with is saved or not.