You ask how it looks in God's eyes if a Christian joins a political organisation. You ask further how one can become a good leader if you do not know about your people's previous politics.
It is true that leaders do need to know all about their people; their politics, their economic circumstances and many other things.
If we were to leave the governing of countries to those who are not Christians, there would be less freedom for the worship of God and for God's Word to reach the people. God wants Christians to have influence in all spheres of life, including politics.
The question that arises from this is, "How should he be involved?" He should not be involved for selfish reasons / to promote a better life for himself and his own tribe while others suffer. There should be no thought of seeking fame or money. His aim should be only that the righteousness of God should be shown and lived out. If this were done, much of the fighting in party politics would disappear. Individual Christians can play a large part in lifting up the righteousness of God in a nation, if God's glory is their only aim.
The work of the church as Christ's body is to bring people to know Jesus as Saviour and teach Christians how to live their lives according to God's principles. Then people who have been so taught can go into the world of politics and live the Christian life as God wants them to, and thus be an influence for God. This has happened in the past.