In the first place, let us remind ourselves that God is ABSOLUTELY IN CONTROL of all that happens in this world. He is never taken by surprise because He is omniscient. Nothing can ever happen, Good or Evil, if He does not permit it to happen.
Yes, He has given us FREE WILL to choose between good and evil, and this is why we are judged at the end of our lives. His judgments are all of them just, because we freely chose to do that evil for which we are condemned. He does not interfere with what we use our Free Will to decide to do. He judges the heart, and marks our good and evil, the moment we decide in our hearts and consent to carrying them out. He does not wait until carried out before judging us or recording our actions in the Book of Life. That is why Jesus said that we are marked Guilty of adultery when we look at a woman lustfully. God does not wait for the act to be performed before marking us Guilty in the Book of Life, for even if after desiring to commit that sin, one thing or the other prevents us from carrying out the act, (either rainfall or an unexpected visitor) we are not exculpated. We are already marked guilty, for God Judges the heart.
So, if after conceiving that evil act in our hearts, we go out to carry it out, we did that because God’s Permissive Will allowed us to carry out that sinful act. This does not mean that God is in support of the evil. He only permitted that the sinful act one chooses with ones Free Will to commit, takes place, and the judgment for that or its punishment awaits the sinner.
The perfect Will of God is what He has decreed or commanded to happen. It is always borne out of His Love and compassion for us. Because of His Infinite love for us, He sometimes allows us to deny ourselves of His perfect will because we have prayed and prayed so much for something which He knows will do us less good than His perfect will. Here His permissive Will takes over. It may be something like asking for something which He has planned for us to have in four years time. Because of our impatience and persistence in asking, He grants it after one year. We then do not get 100% of what His perfect Will had planned for us. We get less because we could not wait for his four years to come. His PERMISSIVE WILL here replaces His PERFECT WILL for us.
Our Lord Jesus Christ is the WAY, THE TRUTH AND THE LIFE. He is the Way to follow to obtain salvation. It is only through Him that we can get to the Father. Some religions have decided not to accept this fact. In error, they believe that they can get to the Father without accepting Jesus as their Lord and Savior. God permitted them to be in that Error. This is His permissive Will. It is not His perfect will that they should remain in that Error till the end and perish eternally.
Jesus has taught us to love one another (even our enemies) and do good to those who hate us. If we love one another and pray for even our enemies as Jesus teaches, there will be peace in the world. Fighting, and wickedness and murder will be drastically reduced and there will be more reasons and more opportunities for people to be happy and give glory to God from whom all good things come.
The Church has been commissioned by Christ to go into the whole world and bring all men to the knowledge of Christ and the gospel. But we cannot achieve this if some people regard us as infidels and enemies who must be killed. If on the other hand we are able to fraternize with all and show them love, and thus stop them from killing us, it is only then that we can approach them more closely and obtain their attention to the gospel of Christ which we preach. It is out of ignorance of the Truth in Christ that some people run the risk of losing their souls. But when they are able to listen and we are more able to preach to them, many will undoubtedly repent and accept the gospel and be saved.
God in His goodness and wisdom has given us the opportunity to have a means of accumulating merits for our crowns of glory in heaven. Supposing God had not permitted the existence of other religions where do we go to for evangelization and winning of souls for Christ with its attendant rewards and acquisition of higher merits, if the entire world were all Catholics who have all accepted Jesus and are obeying the Ten Commandments? What great Favor the Lord has done to the Church by giving us the field upon which to plough and reap the harvest of souls from these other people! We can never thank Him enough for this great good.
In the same vein, Poverty and Riches come from the Lord, so that the rich will have the poor to give alms to and be blessed as well as see the need to thank and give glory to God for making them rich. The poor on the other hand will have the opportunity to rejoice and give praise and glory to God when lifted up through such alms-giving or elevated to become rich through the work of their hands to which the Lord has given success.