""God had given men and women free will to choose whether “spontaneously to accept salvation . . . the Christian faith is not imposed on anyone, it is a gift, an offer to mankind”.
How does the pope reconcile this teaching with infant baptism?""
Good question.
From the Catechism of the Catholic Church:
1250 Born with a fallen human nature and tainted by original sin, children also have need of the new birth in Baptism to be freed from the power of darkness and brought into the realm of the freedom of the children of God, to which all men are called. The sheer gratuitousness of the grace of salvation is particularly manifest in infant Baptism. The Church and the parents would deny a child the priceless grace of becoming a child of God were they not to confer Baptism shortly after birth.
1251 Christian parents will recognize that this practice also accords with their role as nurturers of the life that God has entrusted to them.
1252 The practice of infant Baptism is an immemorial tradition of the Church. There is explicit testimony to this practice from the second century on, and it is quite possible that, from the beginning of the apostolic preaching, when whole "households" received baptism, infants may also have been baptized.
1253 Baptism is the sacrament of faith. But faith needs the community of believers. It is only within the faith of the Church that each of the faithful can believe. The faith required for Baptism is not a perfect and mature faith, but a beginning that is called to develop. The catechumen or the godparent is asked: "What do you ask of God's Church?" The response is: "Faith!"
1254 For all the baptized, children or adults, faith must grow after Baptism. For this reason the Church celebrates each year at the Easter Vigil the renewal of baptismal promises. Preparation for Baptism leads only to the threshold of new life. Baptism is the source of that new life in Christ from which the entire Christian life springs forth.
1255 For the grace of Baptism to unfold, the parents' help is important. So too is the role of the godfather and godmother, who must be firm believers, able and ready to help the newly baptized - child or adult on the road of Christian life. Their task is a truly ecclesial function (officium). The whole ecclesial community bears some responsibility for the development and safeguarding of the grace given at Baptism.
1282 Since the earliest times, Baptism has been administered to children, for it is a grace and a gift of God that does not presuppose any human merit; children are baptized in the faith of the Church. Entry into Christian life gives access to true freedom.
My own take on this:
It is disingenuous to say that Christ's Sacrifice is all-sufficient and there is nothing we can do to merit salvation and then say that we must believe in order to be saved. If there is nothing we can do to affect our own salvation, then even our own faith is moot and Christ died for all... period. As it is, Baptism is the beginning of our life in faith, not the culmination of it. From there, we have our infancy in the Family of God and God, through His Holy Spirit, will raise us.
Just as you don't take away the free will of your children in raising them, there is no conflict between infant baptism and the Christian's duty to conform his life to Christ. We might just as soon say we had violated a child's free will in calling him into this world at his birth.
In his book Intro. to Christianity, he explains it very well. Being a Christian means to turn away (convert) from the material world. This conversion has to be an everyday event. Baptism represents the first conversion. The first time that when asked if you believe in God, Jesus Christ and the Holy Spirit, you respond I - do.
The Pope explains it much better than I ever could, and that book is perhaps the best I’ve read in a long, long, time.