Love Your Neighbor

The two greatest commandments are to love God and to love your neighbor as yourself (Mark 12:33, Luke 10:27, Romans 13:9, Galatians 5:14, and James 2:8).  This also includes your enemies.  He who loves belongs to God for God is love.  As Christians, we love all people of different cultures and religions.  No where are we taught to love only the Christians.  All of mankind was created in the image and likeness of God; therefore we are linked to the entire human race regardless of that person's religion.  Even the Apostle Paul called the pagans in Athens "God's children" (See Acts 17:29).  This is what the Catechism of the Catholic Church says regarding non-Christians:

The Church and non-Christians 
 
839 "Those who have not yet received the Gospel are related to the People of God in various ways."³²⁵

The relationship of the Church with the Jewish People. When she delves into her own mystery, the Church, the People of God in the New Covenant, discovers her link with the Jewish People,³²⁶ "the first to hear the Word of God."³²⁷ The Jewish faith, unlike other non-Christian religions, is already a response to God's revelation in the Old Covenant. To the Jews "belong the sonship, the glory, the covenants, the giving of the law, the worship, and the promises; to them belong the patriarchs, and of their race, according to the flesh, is the Christ",³²⁸ "for the gifts and the call of God are irrevocable."³²⁹

840 And when one considers the future, God's People of the Old Covenant and the new People of God tend towards similar goals: expectation of the coming (or the return) of the Messiah. But one awaits the return of the Messiah who died and rose from the dead and is recognized as Lord and Son of God; the other awaits the coming of a Messiah, whose features remain hidden till the end of time; and the latter waiting is accompanied by the drama of not knowing or of misunderstanding Christ Jesus.

841 The Church's relationship with the Muslims. "The plan of salvation also includes those who acknowledge the Creator, in the first place amongst whom are the Muslims; these profess to hold the faith of Abraham, and together with us they adore the one, merciful God, mankind's judge on the last day."³³⁰

842 The Church's bond with non-Christian religions is in the first place the common origin and end of the human race:

All nations form but one community. This is so because all stem from the one stock which God created to people the entire earth, and also because all share a common destiny, namely God. His providence, evident goodness, and saving designs extend to all against the day when the elect are gathered together in the holy city. . .³³¹

843 The Catholic Church recognizes in other religions that search, among shadows and images, for the God who is unknown yet near since he gives life and breath and all things and wants all men to be saved. Thus, the Church considers all goodness and truth found in these religions as "a preparation for the Gospel and given by him who enlightens all men that they may at length have life."³³²

 844 In their religious behavior, however, men also display the limits and errors that disfigure the image of God in them:

Very often, deceived by the Evil One, men have become vain in their reasonings, and have exchanged the truth of God for a lie, and served the creature rather than the Creator. Or else, living and dying in this world without God, they are exposed to ultimate despair.³³³

845 To reunite all his children, scattered and led astray by sin, the Father willed to call the whole of humanity together into his Son's Church. The Church is the place where humanity must rediscover its unity and salvation. The Church is "the world reconciled." She is that bark which "in the full sail of the Lord's cross, by the breath of the Holy Spirit, navigates safely in this world." According to another image dear to the Church Fathers, she is prefigured by Noah's ark, which alone saves from the flood.³³⁴

Christ commanded His Church to spread the Gospel to all people so that they can be baptized into God's family and come to know Him.  However, it was never our place to judge the hearts and souls of men of other religions.  Can a Buddhist or an atheist be saved?  Who am I to judge their souls? 

The Nostra Aetate,  also does NOT contradict the Catechism of the Catholic Church.  In the Nostra Aetate, the Catholic Church examines her relationship with non-Christians.  Below is what the Nostra Aetate says of these non-Christian religions.  You can read the rest of the document in the Vatican website that I provided below: 

2. From ancient times down to the present, there is found among various peoples a certain perception of that hidden power which hovers over the course of things and over the events of human history; at times some indeed have come to the recognition of a Supreme Being, or even of a Father. This perception and recognition penetrates their lives with a profound religious sense.
 
Religions, however, that are bound up with an advanced culture have struggled to answer the same questions by means of more refined concepts and a more developed language. Thus in Hinduism, men contemplate the divine mystery and express it through an inexhaustible abundance of myths and through searching philosophical inquiry. They seek freedom from the anguish of our human condition either through ascetical practices or profound meditation or a flight to God with love and trust. Again, Buddhism, in its various forms, realizes the radical insufficiency of this changeable world; it teaches a way by which men, in a devout and confident spirit, may be able either to acquire the state of perfect liberation, or attain, by their own efforts or through higher help, supreme illumination. Likewise, other religions found everywhere try to counter the restlessness of the human heart, each in its own manner, by proposing "ways," comprising teachings, rules of life, and sacred rites. The Catholic Church rejects nothing that is true and holy in these religions. She regards with sincere reverence those ways of conduct and of life, those precepts and teachings which, though differing in many aspects from the ones she holds and sets forth, nonetheless often reflect a ray of that Truth which enlightens all men. Indeed, she proclaims, and ever must proclaim Christ "the way, the truth, and the life" (John 14:6), in whom men may find the fullness of religious life, in whom God has reconciled all things to Himself.(4)
  
The Church, therefore, exhorts her sons, that through dialogue and collaboration with the followers of other religions, carried out with prudence and love and in witness to the Christian faith and life, they recognize, preserve and promote the good things, spiritual and moral, as well as the socio-cultural values found among these men.
   
3. The Church regards with esteem also the Moslems. They adore the one God, living and subsisting in Himself; merciful and all- powerful, the Creator of heaven and earth,(5) who has spoken to men; they take pains to submit wholeheartedly to even His inscrutable decrees, just as Abraham, with whom the faith of Islam takes pleasure in linking itself, submitted to God. Though they do not acknowledge Jesus as God, they revere Him as a prophet. They also honor Mary, His virgin Mother; at times they even call on her with devotion. In addition, they await the day of judgment when God will render their deserts to all those who have been raised up from the dead. Finally, they value the moral life and worship God especially through prayer, almsgiving and fasting.
   
Since in the course of centuries not a few quarrels and hostilities have arisen between Christians and Moslems, this sacred synod urges all to forget the past and to work sincerely for mutual understanding and to preserve as well as to promote together for the benefit of all mankind social justice and moral welfare, as well as peace and freedom. 

Nostra Aetate