The reason that we are here, according to Christianity, is that God created us to have a relationship with him. This is why God created a universe fit for human life, and why he laid down guidelines for how to live our lives. Each one of us is created for communion with God; God wants to know us, to love us, and to rejoice with us.
In Islam, the life is to worship Allah. The term "Worship" covers all acts of obedience to Allah. The true Muslim sticks to this purpose throughout all the stages of his life, whether he is a child, adolescent, adult, or an old man. Worshipping Allah makes life purposeful and meaningful, especially within the framework of Islam. According to Islam this worldly life is just a short stage of our life. Then there is the other life. The boundary between the first and second life is the death stage, which is a transitory stage to the second life. The type of life in the second stage a person deserves depends on his deeds in the first life. At the end of the death stage comes the day of judgment. On this day, Allah rewards or punishes people according to their deeds in the first life.
The meaning of life is to know, love, and serve God (Jn 17:3; Sir 1:11-12; Catechism 356, 357, 1721). This is where we will find our fulfillment here on earth and in heaven. Love is the underlying theme throughout the Bible (1 Jn 4:8; Jn 3:16). In fact, there are more than six hundred verses in Scripture that speak explicitly of love. To begin, the creation of human beings was an act of unselfish love by God. He did not need to because He is perfect and needs nothing. But He created us because He knew we would like it. This was an act of love. God exhibited the ultimate act of love when He gave His only Son as the definitive sacrifice to save the world from its sins (Jn 3:16). The Son, Jesus Christ, gave His own life for us when He died on the cross. We are called to this type of unselfish love. Love is most fully expressed when we give ourselves with no interest in gaining something from it. Love is wanting what is best for another simply because it is best for that person! Love is the greatest of virtues. Love is the opposite of selfishness. Love truly makes the world a better place. Without love, we have only emptiness. (My answer continues in the comments)