Christianity does not advocate cutting off your son's foreskin, avoiding clothes of mixed fibers, or giving 10% of your earnings to Pat Robertson.
So it seems as though there is nothing in your way to becoming a Christian!
Since you haven't actually asked a question, I'm going to have to do a little guesswork to try to figure out how to properly address this comment.
I'll start with the easiest one first -- the Bible never even mentions Pat Robertson. So you're free and clear there.
It does frequently mention "tithing", or the practice of devoting 10% of your income to something that God has commanded you to devote it to. Numerous tithes and types of tithes are commanded of the Israelites in the Old Testament. Some of the purposes of these tithes included:
Paying the priests for their work (Numbers 18:24; Nehemiah 10:37)
Providing for the poor (Deuteronomy 26:12)
Financing parties & celebrations (Deuteronomy 14:23-26)
The tithe was a command exclusive to the nation of Israel. It was never commanded of anyone else.
Nonetheless, Christians are expected to provide for the poor (Matthew 6:2-3; Luke 14:13; Galatians 2:12), pay their elders and teachers for their work (1 Corinthians 9:9-11; 1 Timothy 5:17-18), and someone has to finance our parties and celebrations. We simply aren't told to specifically devote exactly 10% toward this end. In fact, the model that Christians have is a much higher model than simply devoting 10% of our income to God's purposes. Our model is the devotion of 100% to God's purposes.
In clarification, I am not suggesting you need to send 100% of your income to Pat Robertson if you want to be a true Christian.
The Bible tells us that we are to be living sacrifices (Romans 12:1). Everything we do should be done to the glory of God (Colossians 3:23). We are commanded to be perfect, even as our Father in Heaven is perfect (Matthew 5:48). This is a much higher calling than a paltry 10%.
The Old Testament commands the circumcision of all male Israelites and males living in the land of Israel. This circumcision was a sign (a reminder, a shadow) of the promises that God made to Abraham, the father of the Israelites (Genesis 17). It also served as a sign (a pointer in the direction) of the future transformation of the heart by the Holy Spirit (Deuteronomy 30:6; Ezekiel 11:19). Ultimately, circumcision pointed to the coming of Jesus Christ, and it was only commanded for those certain select people, descended from Abraham or residing in the nation of Israel.
The apostle Paul makes it abundantly clear in the New Testament that being circumcised cannot save anyone from death and condemnation for their sin, and that circumcision is utterly meaningless with respect to eternity (Galatians 5; 1 Corinthians 7:19; Galatians 6:15).
Therefore, if a Christian decides to cut off his son's foreskin, that is his business. If he decides not to, that is also his business. He has not been specifically commanded either way.
CLOTHES OF MIXED FIBERS
Like tithing and circumcision, avoiding clothes of mixed fibers (Leviticus 19:19; Deuteronomy 22:11) was one of the many commands given to the Israelites and only the Israelites. Nonetheless, there is wisdom in not combining fibers from plant cellulose (such as linen) with fibers from animal protein (such as wool). The fibers have varying degrees of strength, flexibility, etc, and when combined into a single piece of clothing, will probably not produce something that will last very long.
When we read God's revelation in scripture, context is critical. For example, the commands of Moses to the Israelites were exactly that -- commands of Moses to the Israelites. There is no guarantee that they necessarily apply to anyone else unless we have some reason to believe that they do. Often, Moses' words tell us that a particular command or set of commands applies to everyone on earth, such as is the case with the laws against homosexual behavior (Leviticus 20:13-23), and other times, Moses makes it clear that a command or a particular set of commands does NOT apply to everyone on earth but only to the Israelites, such as their dietary laws (Leviticus 11).
It should be pretty obvious that if I am instructing my children, some of the commands I give them will only apply to them, and others are really appropriate for everyone. Moses' commands to the Israelites are no different.
I may, for example, tell my little children never to answer the door. I may also tell them never to kill anyone. If you hear me giving these instructions to my children, you would naturally conclude that the first command for my children is not something that anyone else needs to adhere to. However, if you concluded the same thing about my second command for my children, you would be horribly mistaken. The Laws of Moses are much like this.
Fortunately, the Book of Romans informs us that people have a conscience, and their own conscience will either accuse or excuse them on the day of judgment (Romans 2:12-16). Christ informs us that all the laws that are necessary for us to follow can be summed up in the following way...
Luke 10:26 (NASB)
And He said to him, "What is written in the Law? How does it read to you?" And he answered, "YOU SHALL LOVE THE LORD YOUR GOD WITH ALL YOUR HEART, AND WITH ALL YOUR SOUL, AND WITH ALL YOUR STRENGTH, AND WITH ALL YOUR MIND; AND YOUR NEIGHBOR AS YOURSELF." And He said to him, "You have answered correctly; DO THIS AND YOU WILL LIVE."